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I-10 Phoenix-Tucson bypass study

I-10 Phoenix-Tucson bypass study Final Report

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FINAL REPORT
January 2008
I-10 Phoenix-Tucson Bypass Study
Prepared for
Transportation
Planning Division
Prepared by
in association with
Wilbur Smith Associates
I-10 Phoenix-Tucson Bypass Study
Final Report
Prepared for:
Arizona Department of Transportation
Prepared by:
URS Corporation
in Association with
Wilbur Smith Associates
January 2008
Final Report
I-10 Phoenix-Tucson Bypass Study
Arizona Department of Transportation
i
January 2008
URS Job No. 23445042
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TABLE OF CONTENTS
EXECUTIVE SUMMARY .......................................................................................................ES-1
1.0 INTRODUCTION ...........................................................................................................1-1
1.1 ORIGIN OF THE STUDY ..................................................................................... 1-1
1.2 STUDY PROCESS................................................................................................. 1-2
1.3 PREVIOUS AND ONGOING STUDIES .............................................................. 1-3
1.4 GROWTH SCENARIOS........................................................................................ 1-3
1.5 PURPOSE AND NEED.......................................................................................... 1-6
2.0 I-10 EXISTING AND FUTURE CONDITIONS............................................................ 2-1
2.1 EXISTING CONDITIONS..................................................................................... 2-1
2.2 PLANS FOR IMPROVING I-10............................................................................ 2-3
2.3 PLANS FOR IMPROVEMENTS TO OTHER HIGHWAYS............................... 2-8
2.3.1 US 70 .......................................................................................................... 2-8
2.3.2 US 60 .......................................................................................................... 2-9
2.3.3 US 191 ........................................................................................................ 2-9
2.3.4 I-8................................................................................................................ 2-9
2.3.5 SR 85......................................................................................................... 2-10
2.3.6 South Mountain Freeway.......................................................................... 2-10
2.3.7 I-10 Reliever ............................................................................................. 2-10
2.4 OTHER MODES.................................................................................................. 2-11
2.5 2030 TRAFFIC FORECASTS ............................................................................. 2-12
2.6 NEED FOR BYPASS........................................................................................... 2-13
3.0 POTENTIAL NEW CORRIDORS.................................................................................. 3-1
3.1 INITIAL POTENTIAL CORRIDOR ALTERNATIVES ...................................... 3-1
3.2 FIRST REFINEMENT OF CORRIDOR ALTERNATIVES............................... 3-11
3.3 CORRIDORS FOR EVALUATION – SECOND REFINEMENT...................... 3-14
3.4 EVALUATION CRITERIA AND METHODOLOGY ....................................... 3-18
3.5 FINDINGS............................................................................................................ 3-28
3.6 CORRIDOR FEASIBILITY................................................................................. 3-32
4.0 ENVIRONMENTAL SCAN ...........................................................................................4-1
4.1 FATAL FLAW FACTORS .................................................................................... 4-1
4.2 OTHER ENVIRONMENTAL CONSIDERATIONS............................................ 4-1
4.3 AGENCY COORDINATION .............................................................................. 4-10
4.4 FIELD VISIT........................................................................................................ 4-11
4.5 RESULTS ............................................................................................................. 4-13
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5.0 TRAFFIC FORECASTING METHODOLOGY AND RESULTS ................................ 5-1
5.1 FORECASTING METHODOLOGY..................................................................... 5-1
5.2 FORECASTING RESULTS................................................................................... 5-4
6.0 POTENTIAL CORRIDOR FEATURES......................................................................... 6-1
6.1 CROSS SECTIONS................................................................................................ 6-1
6.2 COST ESTIMATE.................................................................................................. 6-1
7.0 FUNDING OPTIONS......................................................................................................7-1
7.1 OVERVIEW OF TRANSPORTATION FUNDING SOURCES AND
FINANCING MECHANISMS............................................................................ 7-1
7.2 ASSESSMENT OF FUNDING OPTIONS............................................................ 7-4
7.3 CONCLUSIONS AND RECOMMENDATIONS ................................................. 7-6
8.0 PUBLIC AND STAKEHOLDER INPUT....................................................................... 8-1
8.1 INTRODUCTION .................................................................................................. 8-1
8.2 PUBLIC LISTENING SESSIONS – MAY 2007................................................... 8-1
8.3 PUBLIC COMMENTS RECEIVED (PUBLIC LISTENING SESSIONS)........... 8-3
8.4 PUBLIC MEETINGS – PRELIMINARY FINDINGS
NOVEMBER/DECEMBER 2007 ....................................................................... 8-5
8.5 PUBLIC COMMENTS RECEIVED OUTSIDE OF PUBLIC MEETINGS ......... 8-8
8.6 STAKEHOLDER INTERVIEWS........................................................................ 8-11
8.7 NEWSPAPER AND MEDIA COVERAGE ........................................................ 8-14
LIST OF TABLES
Table E-1 West Segment Comparison of Route Distance and Time..................................ES-6
Table E-2 Traffic Reduction on I-10 in Tucson .................................................................ES-9
Table E-3 East Segment Comparison of Route Distance and Time .................................ES-10
Table 2-1 I-10 2005 Average Daily Traffic and Number of Through Lanes....................... 2-2
Table 2-2 Estimate of Planned Number of Lanes and 2030 Model Volumes...................... 2-6
Table 3-1 Initial Stakeholder Responses to Potential Corridor Alternativesa ...................... 3-8
Table 3-2 Combined Stakeholder Responses to Potential Corridor Alternativesa ............... 3-9
Table 3-3 Stakeholder Responses to Refined Corridor Alternativesa ................................ 3-14
Table 3-4 GIS Data Sources............................................................................................... 3-15
Table 3-5 Evaluation Criteria for Alternative Corridors .................................................... 3-18
Table 3-6 Evaluation Criteria 1 .......................................................................................... 3-19
Table 3-7 Evaluation Criteria 2 West and East Segments.................................................. 3-20
Table 3-8 Existing I-10 Speed Limits ................................................................................ 3-21
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Table 3-9 Evaluation Criteria 2 by Overall Corridor Routes ............................................. 3-23
Table 3-10 Evaluation Criteria 3 .......................................................................................... 3-24
Table 3-11 Evaluation Criteria 4 .......................................................................................... 3-25
Table 3-12 Evaluation Criteria 5 .......................................................................................... 3-26
Table 4-1 Sensitive and Federally Listed Species from AGFD.......................................... 4-2
Table 4-2 Data Suggestions from Environmental Stakeholders .......................................... 4-9
Table 4-3 Special Status Cultural Resources in General Proximity of Corridor
Alternatives ........................................................................................................ 4-10
Table 4-4 Environmental Stakeholders .............................................................................. 4-11
Table 5-1 Travel Forecast for Alternative Concepts ............................................................ 5-4
Table 6-1 Estimated Unit Costs............................................................................................ 6-3
Table 6-2 Individual Segment Cost Estimate Summary ...................................................... 6-4
Table 6-3 Proposed Route Cost Estimates ........................................................................... 6-4
LIST OF FIGURES
Figure E.1 Corridor Alternatives and Major Constraints ....................................................ES-4
Figure E.2 East Segment Comparative Routes....................................................................ES-8
Figure 1.1 Arizona’s Future Growth Pattern......................................................................... 1-5
Figure 2.1 2004 Traffic Volumes and Truck Percentage ...................................................... 2-3
Figure 2.2 MAG I-10 Improvements .................................................................................... 2-8
Figure 3.1 Environmental Constraints................................................................................... 3-2
Figure 3.2 Land Ownership................................................................................................... 3-3
Figure 3.3 Topography.......................................................................................................... 3-4
Figure 3.4 Existing Transportation System........................................................................... 3-5
Figure 3.5 Initial Potential Corridors .................................................................................... 3-7
Figure 3.6 Corridor Alternatives – First Refinement .......................................................... 3-12
Figure 3.7 Corridors for Evaluation – Second Refinement................................................. 3-16
Figure 3.8 Alternative Corridor Segments Used in Evaluation........................................... 3-17
Figure 4.1 Grasslands and Riparian Forests........................................................................ 4-14
Figure 4.2 Wildlife Connectivity......................................................................................... 4-16
Figure 4.3 Priority Conservation Areas............................................................................... 4-18
Figure 6.1 Proposed Cross Sections ...................................................................................... 6-2
LIST OF APPENDICES
A Prior and Ongoing Studies
B Technical Memorandum, Travel Demand Forecasting
\ Final Report
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Arizona Department of Transportation
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EXECUTIVE SUMMARY
The I-10 Phoenix-Tucson Bypass Study was conceived to address existing and future traffic
congestion in the two major metropolitan areas of Arizona. Arizona has been one of the fastest
growing states in the nation for the past four decades, and most people believe this trend will
continue. Traffic has increased even faster than the phenomenal population growth.
The purpose of the bypass study is to make a preliminary assessment of the need for and
feasibility of a new transportation corridor that would provide an alternative to I-10 to divert
through traffic out of the congested metropolitan areas.
1.0 OVERVIEW
1.1 Study Process
The study began in April 2007 and was designed to be completed by the end of 2007. A
Technical Advisory Committee (TAC) was formed consisting of representatives from Arizona
Department of Transportation (ADOT), Federal Highway Administration (FHWA), Maricopa
Association of Governments (MAG), Central Arizona Association of Governments (CAAG), and
Pima Association of Governments (PAG). The committee met several times during the course of
the study to provide review and guidance to the study team.
Initial public meetings were held in May 2007 in Benson, Tucson, Eloy, and Buckeye. These
meetings were very well attended, and many verbal and written comments were received
regarding the purpose and need of the bypass, issues and concerns, and the initial array of
potential alternative corridors. A second round of public meetings was held in November and
December. Locations included Benson, Tucson, Casa Grande, Buckeye, Marana, Safford, and
Willcox. The preliminary findings from the study were presented for review and comment.
Verbal comments were summarized on flip charts, comment forms were received and tabulated
and electronic comments were recorded. Presentations were made to PAG and MAG.
ADOT, the State Transportation Board, and the TAC provided a list of stakeholders to be
interviewed. A total of 42 interviews were conducted in May-July 2007. These interviews
provided insight into initial opinions and preferences of the stakeholders and provided
information used to refine the corridor initial alternatives.
A field tour was conducted on September 6 and 7 and hosted by The Nature Conservancy.
Several other agencies with interests in the San Pedro River Valley also participated. The tour
provided information about specific areas of concern in the San Pedro and Aravaipa valleys and
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enabled the study team to visually inspect some of the more critical areas being considered for
the corridor alternatives.
Preliminary findings were presented to the State Transportation Board at a study session on
November 5, 2007. Refined study findings were presented following the second round of public
meetings at a regular Board meeting on December 21, 2007.
1.2 Corridor Alternatives Development
The initial idea for this bypass study came from the State Transportation Board. Based on
discussions at a Board meeting in December 2006, a corridor concept appeared in a newspaper
article. The concept showed a corridor extending from I-10 west of Buckeye to I-10 near Casa
Grande and continuing to I-10 near Willcox. This concept illustrated the fundamental idea that
the State Transportation Board wanted ADOT to study.
The study team took this basic concept and developed a broad array of initial potential corridors.
Refer to Figure 3.5 in Chapter 3. This array of corridors was presented at the initial public
meetings in May to provide a basis for discussion of the fundamental concept and to identify
variations to this initial array of alternatives. Initial graphics showing environmental constraints,
land ownership, topography, and the existing transportation system were also shown to the
public. Through the study process, these graphics were refined and are shown in Figures 3.1
through 3.4.
A Purpose and Need Statement was developed and presented to the public and stakeholders.
Minor refinements were made, and the final statement is presented as follows:
Purpose
• To provide an additional high-capacity transportation corridor to accommodate travel across
southern and central Arizona.
Need
• Provide alternative route to I-10 to relieve traffic congestion on I-10 in the Phoenix and
Tucson metropolitan areas.
• Provide a shorter, faster route through southern and central Arizona that will attract through
trucks and other traffic from I-10.
• Provide a new route that offers an alternative path for I-10 traffic during construction,
maintenance, and incidents.
• Provide a new transportation corridor to serve the expected rapid population growth and land
development in the Sun Corridor.*
• Develop a corridor that is context sensitive to environmental and social elements.
* The Sun Corridor is one of a dozen future mega-metropolitan areas identified in the United States and could stretch
from Prescott to Sierra Vista.
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The following is a brief description of the material covered in each chapter of the final report.
The findings are summarized in Sections 2 through 5 of this Executive Summary.
The need for the bypass corridor was examined by comparing the number of existing lanes on
I-10 to the existing traffic volumes. Plans for future widening of I-10 and other related routes
were also identified. The ability to widen I-10 through Tucson is very limited and provides a
major reason for considering a bypass. These data are presented in Chapter 2.
The initial potential corridors were refined based upon additional information regarding
constraints, input from stakeholders, and the field tour. The final set of alternatives used in the
evaluation is shown in Figure E.1. The major constraint areas including environmental
constraints, Indian reservations, and existing and entitled urban development are also highlighted
in this graphic.
The refined alternatives were evaluated based on criteria derived from the Purpose and Need
Statement. The evaluation is included in Chapter 3.
An environmental scan was prepared to identify the major constraints to the corridors and to
identify environmental issues associated with those corridors. The constraints are shown in detail
in Figure 3.1, and the scan is described in Chapter 4.
Given the very preliminary nature of this study, computerized traffic modeling to forecast traffic
was not prepared. Instead, a manual method was developed, documented in a Technical
Memorandum included in the Appendix and summarized in Chapter 5. These forecasts only
address long trips and through-Arizona traffic. Localized traffic from urban development along
the corridors is not included. This local urban travel demand is being addressed in other state,
regional, or local studies. The forecasts developed for this study are believed to provide a
reasonable basis for determining the amount of traffic that might be diverted from I-10 and the
volume of long-trip and through traffic that might use the potential corridor. The forecasts were
helpful in determining need and feasibility.
The basic roadway cross-section needed for the corridor was identified based on the long-trip
needs. Urban traffic on the corridors may require additional lanes. A very preliminary, order of
magnitude cost estimate was made for the corridor alternatives. This information is discussed in
Chapter 6.
Potential sources of funding were identified for the corridor and discussed in Chapter 7.
The public meetings and stakeholder involvement are documented in Chapter 8.
Sonoran Desert
National Monument
Ironwood Forest
National Monument
San Pedro Valley
Saguaro National
ParkTucson
Mountain District
Santa
Catalina
Mountains
Santa Teresa
Wilderness
Aravaipa
Canyon
Wilderness
Galiuro
Mountains
Rincon
Mountains
Eagletail
Mountains
Wilderness Tonopah
Valley
Goodyear
Sierra Estrella
Wilderness
Organ Pipe
National Monument
and Wilderness
Aravaipa Valley
Coronado
National
Forest
Coronado
National
Forest
Coronado
National
Forest
Pinaleno
Mountains
Willcox
Playa
Sulphur
Springs
Valley
Allen
Flat
Proposed
Park
Avra
Valley
Proposed
Park
South Mountain
Park
Haley Hills
San Carlos Apache Indian Reservation
Tucson
Marana
Eloy
Casa Grande
Phoenix
Florence
Gila Bend Coolidge
Willcox
Benson
San Xavier
Gila River
Indian Community
Safford
Maricopa
Buckeye
PIMA
PINAL
MARICOPA
GRAHAM
GILA
COCHISE
GREENLEE
APACHE
NAVAJO
C1
C2
D1
D2 E1
E2
F1
F2
F3
G
H
I
K1
K2
L
M1
M2
Legend
0 2.5 5 10 15 20
Miles
Scale Data Source: ALRIS 1997 - 2005, Bureau of Land Management,
ADOT ATIS 2005, ADOT HPMS 2005, USGS,
Bureau of Transportation Statistics
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Figure E.1
Corridor Alternatives
and Major Constraints
II--10 Phoeniix--Tucson Bypass Sttudy
Major Constraints
Major Rivers
State Routes
Existing Urban Land
Entitled Land
Indian Reservation
Environmental Limitations to Corridor
Disclaimer:
While every effort has been made to ensure the accuracy
of this information, the Arizona Department of Transportation
makes no warranty, expressed or implied as to its accuracy
and expressly disclaims liability for the accuracy thereof.
Corridor locations are conceptual. Alignments would be determined
following the completion of appropriate design and environmental
studies.
Final Report
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Arizona Department of Transportation
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2.0 FINDINGS
The determination of need for the project is based on the Purpose and Need Statement. The
following summarizes the findings of this study regarding the need. The discussion is separated
into two segments: West Segment (Buckeye to Casa Grande) and East Segment (Casa Grande to
Willcox).
2.1 West Segment
The SR 85/I-8 route is designated as the Phoenix I-10 Bypass. I-8 is a four-lane interstate
highway that is currently underutilized. SR 85 is being upgraded to a four-lane divided limited
access highway. When the improvements to SR 85 are completed, a free-flow bypass will exist
for through traffic to avoid the Phoenix area. This bypass will probably have the capacity to
accommodate the bypass traffic demand for many years.
When extensive urban development occurs in the Tonopah Valley-Buckeye-Goodyear-Maricopa
area, additional freeways may be needed to serve the urban traffic. Corridor C was derived from
the MAG Hassayampa Valley Roadway Framework Study. The corridor is planned to be a part
of the expanding urban freeway system and would link into other components of that system.
The need for the roadway is largely dependent upon the timing and rate of development in that
part of Maricopa and Pinal counties.
Selection of Route: Only one new corridor alternative was identified for the west segment due to
major constraints created by the Sonoran Desert National Monument, the Estrella Mountains, the
Gila River, two Indian reservations, and entitled lands in Goodyear and Maricopa. Corridor C
could connect to I-10 north of Casa Grande (Corridor C2) or connect to I-8 (Corridor D1). Refer
to Figure E.1.
Relieve Traffic Congestion in Phoenix: The projected traffic volumes by MAG in Phoenix
indicate that all planned freeways will be operating at full capacity in 2030. The traffic forecasts
prepared for this study indicate that the west segment could relieve I-10 by 44,100 vehicles per
day (vpd) in 2030 and 97,100 vpd in 2050. The increase in diversion between 2030 and 2050
reflects the acceleration of growth in western Maricopa County and the worsening traffic
congestion in Phoenix. The traffic to and from western Maricopa County that wants to go to
Casa Grande, Tucson or points east, would use the potential bypass and avoid going through the
rest of the Phoenix area. The traffic reduction equates to one lane in each direction in 2030 and
two lanes in each direction in 2050.
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Provide a Shorter, Faster Route: Table E-1 provides a comparison of the distance and time on
I-10, SR 85/I-8 and Corridor C. Corridor C is approximately 10 miles shorter than existing I-10
and 15 miles shorter than the current SR 85/I-8 bypass. It would reduce travel time compared to
existing I-10 by 14 minutes in off-peak and 31 minutes in peak times based upon projected 2030
conditions. In comparison with the SR 85/I-8 existing bypass, Corridor C would provide travel
time savings of approximately 8 minutes in the off peak and 10 minutes in the peak.
Table E-1
West Segment Comparison of Route Distance and Time
Travel Time (minutes) Time Savings (minutes)b
Routea
Lengths
(miles) Off Peak Peak Off Peak Peak
I-10 100 92 128 – –
SR 85 / I-8 105 86 97 6 31
C1-D1 90 78 87 14 41
a I-10 MP 98 west of Buckeye to I-10/I-8 interchange in Casa Grande
b As compared to I-10 in 2030
If Corridor C is constructed at some future date to serve the expanding urban area, it will likely
replace the function of SR 85/I-8 as the I-10 Bypass because it will be a shorter, faster route.
Provide an Alternative Route to I-10: The potential new corridor would provide an additional
alternative route to I-10; however, SR 85/I-8 already provides an alternative from Buckeye to
Casa Grande. Some planned additional freeways in Phoenix will also provide alternative routes
within the urban area.
Serve the Expected Growth in the Sun Corridor: Population forecasts provided by MAG from
the Hidden Valley Roadway Framework Study indicate the population of the portion of Maricopa
and Pinal counties that would be generally served by a potential corridor such as Corridor C
could range from 400,000 to 700,000 in 2030 and into the millions in later years. When growth
of this magnitude occurs, a new corridor such as Corridor C would be needed.
Develop a Corridor that Is Context Sensitive to Environmental and Social Elements: If the
corridor is planned and preserved, it can fit well within the future urban fabric planned for the
area. There is a wildlife corridor extending between the Sonoran Desert National Monument and
the Sierra Estrella Wilderness. Provisions for maintaining this corridor would need to be
incorporated into the design of a roadway corridor.
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2.2 East Segment
The East Segment would extend from I-10 in Casa Grande to I-10 near Willcox. Of the several
alternative corridors shown in Figure E.1, Corridor F1 would connect to I-10 north of Casa
Grande while Corridor G would be more or less a direct eastward extension of I-8 and
Corridor E1 would connect with I-10 in Eloy. If F1 were chosen as the corridor, then
Corridors C1 and C2 would also have to be chosen and constructed to provide a continuous
bypass.
To simplify the comparative summary of findings, it was decided to use alternative Corridors G
and E1 to form the alternatives. These corridors connect into I-10 at a location that would enable
traffic to continue to use SR 85/I-8 as the West Segment I-10 Bypass or they could connect into
either Corridor C2 or D1 if a new I-10 Bypass route were chosen and constructed for the West
Segment. On this basis, alternative routes comprised of various corridor sections were chosen to
illustrate the findings of this preliminary assessment of the East Segment.
Selection of Routes for Comparison: The numerous potential corridor alternatives that were
developed and studied are shown in Figure E.1. From these several possibilities, four corridors
were chosen that connect to I-8 and appear to be logical potential corridors that would meet the
purpose and need for the east segment of the bypass. These four corridors are labeled as
“Routes” and are shown in Figure E.2. All of these routes connect into the I-10/I-8 interchange
either as a new leg of that interchange or via existing I-10. Other corridors and sections identified
in Chapter 3 were not eliminated but simply were not used in this summary analysis to determine
whether or not there are corridors that could meet the purpose and need of the bypass.
The M2 section that would extend to Safford and utilize US 191 to I-10 was not included
because it is a longer route than existing I-10. The D1 section was modified to connect into the
I-10/I-8 interchange as the south leg. This revision is compatible with concepts being studied as
part of the Southern Pinal/Northern Pima Corridor Definition Study. The E1 section could be
extended to the west to connect with the D1 section. It was stopped at I-10 in Eloy just to provide
more variation in the comparative summary evaluation.
Relieve Traffic Congestion in Tucson: Traffic volumes on I-10 through Tucson in 2005 exceed
150,000 vpd. Forecasts by PAG indicate that traffic demand on I-10 in 2030 could exceed
300,000 vpd. ADOT is constructing or has plans to build four lanes in each direction through
Tucson. That is the maximum number of lanes that can fit within the very confined right-of-way.
Since the estimated capacity of an eight-lane freeway is 196,000 vpd, some relief to the future
traffic is needed.
Sonoran Desert
National Monument
Ironwood Forest
National Monument
Buenos Aires
National Wildlife
Re fuge
Mt. Wrightson
Wilderness
Las Cienegas
NCA
San Pedro Valley
Saguaro National
ParkTucson
Mountain District
Santa
Catalina
Mountains
Santa Teresa
Wilderness
Aravaipa
Canyon
Wilderness
Galiuro
Mountains
Rincon
Mountains
Aravaipa Valley
Coronado
National
Forest
Coronado
National
Forest
Coronado
National
Forest
Pinaleno
Mountains
Willcox
Playa
Sulphur
Springs
Valley
Allen
Flat
Proposed
Park
Avra
Valley
Proposed
Park
Haley Hills
Tohono O'odham Nation Tucson
Marana
Eloy
Casa Grande
Florence
Coolidge
Willcox
Benson
San Xavier
Safford
Maricopa
Route 1
Route 2
Route 3
Route 4
PIMA
PINAL
COCHISE
GRAHAM
MARICOPA
SANTA CRUZ
GILA GREENLEE
D1
E1
F2
G
H
I
K1
K2
L
M1
Legend
0 2.5 5 10 15 20
Miles
Scale Data Source: ALRIS 1997 - 2005, Bureau of Land Management,
ADOT ATIS 2005, ADOT HPMS 2005, USGS,
Bureau of Transportation Statistics
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Figure E.2
East Segment Comparative Routes
II--10 Phoeniix--Tucson Bypass Sttudy
Major Rivers
State Routes
Disclaimer:
While every effort has been made to ensure the accuracy
of this information, the Arizona Department of Transportation
makes no warranty, expressed or implied as to its accuracy
and expressly disclaims liability for the accuracy thereof.
Corridor locations are conceptual. Alignments would be determined
following the completion of appropriate design and environmental
studies.
Major Constraints
Existing Urban Land
Entitled Land
Indian Reservation
Environmental Limitations to Corridor
Final Report
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Arizona Department of Transportation
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The potential traffic reduction in Tucson in 2030 and 2050 is shown in Table E-2. Routes 1, 2,
or 3 would reduce traffic on I-10 by 14,500 vpd in 2030 and 20,000 vpd in 2050. This volume
equates to approximately 0.3 lanes in each direction in 2030 and 0.4 lanes in each direction in
2050. The reduction in traffic amounts to 7% to 10% of the planned roadway capacity
(196,000 vpd). This reduction would help relieve congestion in Tucson by a modest amount.
Table E-2
Traffic Reduction on I-10 in Tucson
2030 AADTa
Percent of
Capacityb 2050 AADTa
Percent of
Capacityb
Route 1, 2, or 3 14,500 7% 20,000 10%
Route 4 32,700 17% 72,800 37%
a Average annual daily traffic total two-way.
b Capacity of eight lanes = 196,000. See Travel Demand Forecasting Technical Memorandum, October 4, 2007, by
Wilber Smith Associates, p. 19 for derivation of capacity.
With Route 4, the reductions would be greater than with Routes 1, 2, and 3. The amounts equate
to 17% and 37% of the planned capacity. The reduction in 2050 equates to 1.5 lanes in each
direction. Some of this reduction to I-10 traffic would come from the diversion of I-19 traffic
going to/from Mexico but not destined for Tucson. This I-10 through traffic would join I-10 east
of Tucson if headed for New Mexico or northwest of Tucson if headed for Phoenix or California.
If both Route 4 and either of the Routes 1, 2, or 3 are built, the greatest reduction in traffic in
Tucson would be realized. The amounts equate to 20% in 2030 and 42% in 2050 of the planned
roadway capacity and would make a significant difference in the excess demand and traffic
congestion on I-10 in Tucson.
Provide a Shorter, Faster Route: Table E-3 provides comparative data on distances and travel
time for I-10 (in 2030) and for the four route alternatives used in this summary evaluation.
Routes 1, 2, and 3 would provide a shorter and quicker route than existing I-10. Distance savings
range from 6 to 15 miles and the time savings would be approximately 13 to 17 minutes in the
off-peak hours and 33 to 36 minutes in the peak hours. The shorter, faster routes will attract
through traffic from I-10, including many large trucks that have no destination in the Tucson
area. The distance and time savings can help to reduce the cost of goods and services as well as
benefiting all motorists on the new bypass and those that remain on I-10 because of the reduced
congestion.
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Table E-3
East Segment Comparison of Route Distance and Time
Travel Time (minutes) Time Savings (minutes)b
Routea
Lengths
(miles) Off Peak Peak Off Peak Peak
I-10 150 132 167 – –
Route 1 135 116 131 16 36
Route 2 144 119 134 13 33
Route 3 138 115 131 17 36
Route 4 178 153 170 (21) (3)
a I -10/I -8 interchange in Casa Grande to I -10 MP 348 east of Willcox
b As compared to I-10 in 2030
Route 4 would be longer and would not reduce travel time for I-10 through traffic; however, by
reducing congestion on I-10, it would provide benefits to motorists on I-10.
Provide an Alternative Route to I-10: Currently there are no alternative routes to I-10 through
southern Arizona. Traffic incidents or construction can create untenable situations on this
essential lifeline for Tucson and Phoenix and much of the Southwest. The potential bypass routes
would provide an alternative route to I-10. With appropriate traveler information systems,
motorists could choose the alternative route if there are unfavorable conditions on I-10 even if
they might have otherwise chosen to stay on I-10. Routes 1, 2, and 3 require motorists to make
the route decision near Casa Grande for eastbound travelers and near Willcox for westbound
travelers. As a result, the alternative route would only apply to long distance and through trips.
Route 4, because it is longer than I-10, would not attract I-10 through trips except when traffic
conditions in Tucson are at their worst. However, because Route 4 roughly parallels I-10 from
Casa Grande to Tucson, it would provide numerous opportunities for motorists to divert from
one route to the other depending on traffic conditions and advance information provided by
traveler information systems. I-10 between Casa Grande and Tucson is expected to be more
heavily traveled than I-10 east of Tucson. Route 4 may provide a more valuable alternative
corridor than Route 1, 2, or 3.
Serve the Expected Growth in the Sun Corridor: Population in Arizona is projected to
increase from 6.2 million in 2006 to 10.3 million in 2030. Population forecasts for 2050 range
from 12.8 million to 16 million. The five-county study area (Maricopa, Pinal, Pima, Cochise, and
Graham) includes about 83% of the current population of the state and is projected to contain
85% in the future. Pinal County is expected to be the fastest growing on a percentage basis and
could have an urban area comprised of the cities of Maricopa, Casa Grande, Coolidge, Eloy, and
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Florence that could exceed the population of the current Tucson Metropolitan Area. Preservation
of corridors through this area is very important to the long-term vitality of this growing area.
Most of the growth is currently expected to occur west of SR 79 in Pinal County. Routes 1, 2,
and 3 would provide an east-west corridor that could be part of the major highway plan for the
area. Route 4 would pass through more of the area expected to develop and thus may serve a
greater need in Pinal County.
Routes 1, 2, and 3 could also serve areas that currently are not expected to be highly urbanized.
Communities that could receive significant economic stimulus from the bypass include all of
eastern Pinal County including the communities of Dudleyville, San Manual, and Mammoth. In
addition, Cochise County and Willcox could receive economic stimulus. If a connection is made
to Safford (Corridor M2 in Figure E.1), a linkage would be provided between central Pinal
County and the largest urban center in Graham County thus connecting two areas that are
expected to grow significantly over the next few decades.
Develop a Corridor that Is Context Sensitive to Environmental and Social Elements: The
eastern end of Routes 1, 2, and 3 is comprised of Sections F3, M1, L, K1, and K2. All of these
sections are near areas that have numerous environmentally sensitive properties. The corridors
have been identified to avoid encroaching on any of the protected lands, but the corridors are in
general proximity to several national forests, wilderness areas, areas of critical environmental
concern, and areas set aside for preservation of wetlands and riparian habitat. Some stakeholder
agencies have expressed great concern regarding the potential impact that a new highway would
have primarily due to the potential inducement of urban development that could compete for the
groundwater supply in the river watersheds that makes the area unique and valuable as a natural
preserve. The concern is primarily directed at the San Pedro Valley and to a somewhat lesser
extent the Aravaipa Valley.
The routes through these areas would need to accommodate wildlife crossings, preservation of
native vegetation, and incorporate design features that enhance the area and make the roadway
compatible with its surroundings.
Minimizing the potential of urban development in the most sensitive areas would need to be
addressed. Selection of interchange locations would be the most critical element. Since the
corridors mostly pass through State Trust Lands, extensive coordination with the Arizona State
Land Department would be needed.
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Section M1 of Route 1 would pass through approximately 14 miles of rugged mountainous
terrain. Currently, this area is only accessible by four-wheel-drive vehicles. In the middle of the
section, those jeep trails are difficult to use by any vehicle. Design of a roadway through this
area will require exceptional effort to minimize impacts and develop a pleasing roadway that
does not create an unrepairable scar on the landscape. If properly designed, the roadway would
provide a very scenic drive for motorists.
Route 4 would avoid the sensitive areas that have received the most discussion from stake-holders;
however, it is not without controversy. The Avra Valley west of the Tucson Mountains
is an environmentally sensitive area that lies between the Ironwood National Monument and the
Saguaro National Park Tucson Mountain District. Several people at public meetings expressed
concern about a new roadway corridor in that general area.
The Tucson Mitigation Corridor (approximately 4.25 square miles) was established as mitigation
for construction of the Central Arizona Project Canal. This area lies along Sandario Road south
and west of Tucson Mountain Park. The Tohono O’odham Indian Reservation is on the west side
of Sandario Road. For a two-mile long stretch, the right-of-way for Sandario Road provides the
only space between the Indian Reservation and the Mitigation Corridor. For this roadway
corridor to be viable, the ability to work out some land exchange with the Mitigation Corridor
would be needed.
3.0 FEASIBILITY
The several corridor alternatives were evaluated to determine feasibility based on avoidance of
protected environmental areas, engineering challenges, benefit/cost, and public/stakeholder
acceptance. Based on the preliminary assessment made as part of this study, there are several
corridors that appear to be feasible.
All of the corridors shown in Figure E.1 avoid direct encroachment of all protected lands and
Indian reservations with the exception of a two-mile stretch of Corridor H as discussed above.
With this one potential exception, no other fatal flaws were found.
All of the corridors appear to offer routes that can be engineered and constructed. The most
difficult section is M1. A very preliminary route location was developed that appears to be
feasible. The cost per mile would probably exceed most other rural sections but would be
somewhat comparable in complexity to SR 87 through the area near the Maricopa/Gila County
line. Several major bridges with tall piers may be needed in this section, but it appears that none
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of them would be long-span structures. It appears that grades can be kept to 6% or less with
some cuts and fills reaching 200 feet in height.
The second-most-challenging section is K1 in the San Pedro Valley. It would pass through
rolling terrain with numerous washes on the western slope of the Galiuro Mountains. Based on a
very preliminary examination of topographic mapping, no major engineering issues were noted.
Routes 1, 2, and 3 are projected to carry 17,000 vpd in 2030 and 24,000 vpd in 2050. These
forecasts are based on growth of long-trip and through traffic and do not include traffic that
might be generated by urban growth along the corridor. By comparison, today I-10 east of
Benson carries approximately 15,000 vpd with 30% to 45% heavy trucks. I-8 carries less than
10,000 vpd today. Data supplied by FHWA indicate that in 2005, of the national rural interstate
system (30,000 miles), 22% carried fewer than 10,000 vpd and 52% carried fewer than
20,000 vpd. The projected traffic volumes on the alternative corridors for the I-10 Bypass fall
well within the range expected on rural interstates. A formal benefit cost analyses has not been
conducted.
There is considerable stakeholder opposition to Routes 1, 2, and 3 due to the proximity to
environmentally sensitive areas and concern that a new highway would attract urban
development. The areas are unique due to the riparian habitats along the San Pedro River and
Aravaipa Creek. Urban development would probably draw groundwater that is a critical part of
the watersheds of these two flowing streams and, therefore, could jeopardize years of effort to
protect the water sources for restoration and conservation of these rivers.
Routes 1, 2, and 3 pass through areas that are surrounded by mountain ranges that are in the
Coronado National Forest. The valleys are generally undeveloped and are mostly State Trust
Lands. As a result, a vast sparsely populated area is created that provides habitat for many large
mammals, numerous bird and fish species (some federally protected species), and some unique
native grasslands. Some stakeholders wish to retain this area as a large undeveloped “preserve”
and have the opinion that all growth should take place in the existing major urban areas.
On the other hand, much of the developable land is State Trust Land which is to provide the
maximum financial return to benefit the public education system. Should, or can, all of this land
be protected and left undeveloped? There may be long-term benefits to Arizona of providing
economic stimulus to existing small communities near the corridors and even development of
new small communities. The new communities could give people an opportunity to live near
major preserved areas such as the national forests.
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Decisions about where growth should take place are well beyond what can be addressed in this
study. Since currently there are no adopted land use plans that include urban development in
eastern Pinal County or in the more sensitive areas of Routes 1, 2, and 3, it is reasonable to
assume that urban development in those areas is not desired. Such plans can change in the future.
If a new highway corridor were to be proposed, local jurisdictions and counties may view future
land use in the corridor areas in a different light.
4.0 ROADWAY CROSS-SECTION AND COST ESTIMATES
For the bypass to divert significant traffic from I-10, it needs to provide free-flow conditions that
make the route faster than staying on I-10. Truck traffic would likely be a major component of
the bypass traffic. Given the Arizona terrain, grades (inclines) will be encountered so that trucks
will not always be able to maintain speeds of smaller vehicles. As a result, a four-lane divided
highway appears to be the minimum acceptable roadway. A two-lane highway may be con-sidered
to establish the corridor, but a four-lane roadway will be needed to divert much traffic.
A standard ADOT cross-section with a minimum right-of-way of 308 feet is recommended.
Additional right-of-way will be needed for interchanges, cut and fill slopes, and some drainage
features.
The order of magnitude cost estimates for the entire 250 mile corridor alternatives range between
$6 and $8 billion. The east segment (150+ miles) would cost $2 to $3 billion. The lower cost per
mile for the East Segment compared to the West Segment is due to rural conditions instead of
urban which results in fewer interchanges per mile, less expensive interchanges, and two lanes
each direction instead of three.
5.0 FUNDING
The bypass cannot be constructed with current funding levels. The federal and state fuel tax rates
have not been increased for almost 15 years, and the receipts have been increasing at a slower
rate than traffic increases due to more fuel-efficient vehicles and some alternative fuel usage.
Construction cost increases have far outstripped any highway user fund increases. As a result,
recent projections indicate that the Federal Highway Trust Fund could be approximately
$4 billion in the red by 2009. It would take a 10-cent increase in both the federal fuel tax
(assuming Arizona continues to get its current percentage) and the Arizona fuel tax and to devote
the entire amount of both increases to construct the complete bypass.
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The bypass might be built as a toll road. Very preliminary estimates indicate that it may be
difficult to fund the full amount through tolls because traffic volumes are sensitive to tolling
rates. The trucking association has indicated opposition to toll roads.
6.0 PUBLIC AND STAKEHOLDER OPINIONS
Based upon the stakeholder interviews conducted during the study, all twelve cities contacted
expressed general support for the concept of a new highway corridor. Some cities preferred
certain corridors and opposed others. Of the five counties contacted, three expressed support for
the concept of a new highway corridor while Pima County passed a resolution in December
opposing any new corridor for the I-10 Bypass in the county. Cochise County Board of
Supervisors is opposed to the bypass corridor in the San Pedro Valley.
The Arizona Trucking Association did not support the concept due to concern about funding and
value. Similarly, the T.I.M.E. organization expressed concern that discussions of the I-10 Bypass
might detract from the efforts to fund and construct improvements to I-10. The Union Pacific
Railroad expressed no interest in investing in a new rail corridor since they are investing heavily
in double tracking the existing corridor.
The Arizona Game and Fish Department, the Nature Conservancy, the Cascabel Working Group,
the Defenders of Wildlife and several other environmental-oriented groups expressed significant
opposition to a new corridor particularly in environmentally sensitive areas including the
Araviapa Valley, the San Pedro Valley and the Avra Valley.
The public meetings were all very well attended and scores of comments were received and
recorded. Major themes from these comments are summarized in Chapter 8. Many people were
opposed to some or all of the corridor options due to concern about adverse impact on the
environment and wildlife, impact to rural lifestyles and agricultural lands, and cost. Some people
questioned the population and traffic forecasts based upon limitations on water and petroleum
supplies. Others opined that the corridors east of Tucson would not divert sufficient traffic from
I-10 in Tucson to justify the cost of the bypass or its potential adverse affect on the environment.
Other attendees at the public meetings expressed support for the concept and cited the need to
accommodate continued increases in traffic (particularly trucks) and to preserve corridors
through the rapidly developing areas. Many people believe that major improvements are needed
to the state’s transportation system of highways and railroads.
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7.0 CONCLUSIONS
a. Stakeholders and the public emphasized the most pressing need is to widen and improve I-10
to the maximum extend reasonable, complete the SR 85/I-8 bypass, build the planned
freeway system in the greater Phoenix Metropolitan Area, widen and improve US 60/US 70
from Apache Junction to Safford.
b. The expected continued rapid growth in Arizona will place a huge burden on the state’s
highway system. The emerging Sun Corridor is projected to be home to 10 million or more
residents over the next few decades. Identification and preservation of future transportation
corridors to serve this mega-metropolitan area is essential to the livability of the area and its
economic vitality.
c. Based upon this preliminary assessment, there appears to be a need for an I-10 bypass.
Several alternative corridors have been identified that would offer some relief to traffic
congestion in the Phoenix and Tucson metropolitan areas, would provide a shorter and faster
route, would provide an alternative route to I-10, and would serve the rapidly developing Sun
Corridor.
d. All potential I-10 bypass corridors must pass through central Pinal County where substantial
growth is taking place. Large blocks of land have already been approved for development or
“entitled.” Preservation of a corridor through this area should be of very high importance.
e. All identified alternative corridors appear to be technically feasible and can be located so that
none would encroach on any currently preserved lands (with the possible exception of
Corridor H). Those corridors that would pass through the San Pedro Valley or the Aravaipa
Valley are opposed by very organized and vocal groups that want these valleys to remain
largely undeveloped to preserve the ground water sources for these streams and the wildlife
habitat. There is opposition to the I-10 Bypass in Avra Valley by the Pima County Board of
Supervisors and some residents of the area.
f. Due to the proximity of the potential corridors to large preserved lands, roadways would
need to be designed using context sensitive elements to accommodate wildlife crossings
where needed and to incorporate aesthetic treatments that help to blend the roadways into the
existing environment.
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g. Much of the potential corridors would be on State Trust Land. Early coordination with the
State Land Department will be needed.
h. Major expansions of existing transportation funding sources and new funding sources are
needed to meet the needs in Arizona and particularly to construct a new 250-mile highway.
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1.0 INTRODUCTION
The I-10 Phoenix-Tucson Bypass Study was requested by the Arizona State Transportation
Board. The purpose of the study is to make a “Preliminary assessment of the need and feasibility
for a new transportation corridor that would provide an alternative to I-10.” In particular, the
study is to determine if there is a need for a new major highway corridor through the state that
would provide an alternative route to Interstate 10 (I-10) through the Phoenix and Tucson
metropolitan areas and determine if there are one or more potentially feasible corridors for such a
route.
1.1 ORIGIN OF THE STUDY
Members of the State Transportation Board recognized that I-10 through the Tucson area is
getting more congested every day and that severely limited right-of-way limits the widening of
I-10 to four lanes in each direction. With recent forecasts by the Pima Association of
Governments (PAG) of over 200,000 vehicles per day (vpd), I-10 will become very overloaded.
In December 2006, the idea of an I-10 bypass was first discussed informally by the State
Transportation Board. A newspaper article appeared in the Arizona Daily Star that reported on
this meeting and suggested a bypass route that would depart from I-10 between Willcox and
Benson, cross I-10 in the vicinity of Casa Grande, and rejoin I-10 west of State Route (SR) 85.
Such a corridor could offer a shorter, faster route that would divert through traffic, including
truck traffic, out of Tucson and Phoenix and thereby offer some congestion relief in these
metropolitan areas.
On January 16, 2007 C.H. Huckelberry, Pima County Administrator, sent a letter to Si Shorr,
Vice Chairman of the State Transportation Board, supporting the idea of such a bypass and
identifying some of the expected benefits. He also suggested that the corridor be multimodal
including railroad and utility corridors. Similarly, on January 18, 2007, Richard Myers,
Chairman of the Southern Arizona Leadership Council, sent a letter to Joe Lane, Chairman of the
State Transportation Board, supporting the need for a study of such a bypass.
On January 18, 2007, the State Transportation Board requested that the Arizona Department of
Transportation (ADOT) Transportation Planning Division (TPD) undertake a study of the I-10
Phoenix-Tucson Bypass. URS Corporation (URS) was selected to conduct this study and
received a task order dated March 27, 2007.
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1.2 STUDY PROCESS
The study process generally followed the scope of services included in the Request for Proposal
and further defined in the URS proposal dated February 27, 2007. The State Transportation
Board requested that the study be completed as rapidly as possible. A six-month schedule was
proposed. Ten tasks were identified as follows:
1. Identify and describe all relevant studies that have been completed are ongoing.
2. Identify the potential general corridor or corridors.
3. Estimate travel demand.
4. Identify the number of lanes and road cross section.
5. Estimate the cost.
6. Identify potential fatal flaws and other environmental challenges.
7. Identify potential funding mechanisms.
8. Make recommendations to the State Transportation Board as to whether the bypass
warrants additional study.
9. Work with a Technical Advisory Committee (TAC) and interview key stakeholders.
10. Carry out two rounds of public meetings.
ADOT TPD appointed a TAC comprised of Cherie Campbell (PAG), Bob Hazlett (Maricopa
Association of Governments [MAG]), Bill Leister (Central Arizona Association of Governments
[CAAG]), Jermaine Hannon (Federal Highway Administration [FHWA]), and Dale Buskirk
(ADOT TPD) as chairman. Five TAC meetings were held: April 25, June 5, August 14,
September 25, and November 26, 2007.
The study team was asked to proceed immediately with setting up the first round of public
meetings held May 14-17 and with interviews of key stakeholders. An initial set of potential
corridor alternatives was developed based upon ideas provided by the State Transportation Board
and ongoing studies by MAG and PAG, and by ideas provided by the TAC and study team
members. This initial set of alternatives was shown in the public meetings and to the
stakeholders during interviews. The potential alternatives served to generate comments and other
ideas from the public and stakeholders. The research to identify and describe previous and
ongoing studies provided additional ideas for alternative corridors and provided a wealth of
information to be used in refining and evaluating the alternatives.
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Based upon the input from the public and stakeholders, the number of potential alternatives was
reduced and refined and some additional variations were added. This set of alternatives then was
subjected to additional refinement and analysis by the study team to arrive at a refined set of
alternatives that appear to be feasible. Traffic forecasts were prepared for these alternatives.
They were evaluated and documented in this report. Roadway cross sections, cost estimates, and
funding mechanisms were identified.
Preliminary findings were presented to the State Transportation Board at a study session on
November 5, 2007. Further refinements were made and taken to the public in a second round of
public meetings held in November and December. The study findings were presented to the State
Transportation Board on December 21, 2007. Substantial public and agency comments were
received during the study process, through the public meetings and at the Board meeting.
1.3 PREVIOUS AND ONGOING STUDIES
A preliminary list of identified studies was prepared and discussed with the TAC at the April
meeting. Additional studies were added to the list. Through interviews with stakeholders, even
more studies were identified. The final list of studies identified and reviewed is provided in
Appendix A.
1.4 GROWTH SCENARIOS
Over the past few decades, Arizona has been one of if not the fastest growing states in the nation.
It is hard to predict the rate of growth over the next few decades, but many people believe that
the rate of growth will continue at a rapid pace.
The U.S. Census Bureau, Population Division, Interim State Population Projections, 2005 stated
a 2000 population of 5,130,632 and 2030 projections of 10,712,397 for the State of Arizona. This
forecast indicates the population of Arizona will more than double (108.8 percent change) in the
next 25 years.
Information obtained from the Arizona Department of Economic Security, Research
Administration, Population Statistics Unit provides an breakdown of population projections by
Arizona County for the years 2006 and 2030. Ultimate buildout forecast provided by MAG
indicates that Arizona could have 16 million population by 2050.
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2006 2030
Percent
Growth
2006-2030 2050
Percent
Growth
2030-2050
Arizona 6,239,482 10,347,543 65.8% 16,000,000 54.5%
Maricopa 3,764,446 6,207,980 64.9% 9,553,768 53.9%
Pinal 269,892 852,463 215.9% 1,624,774 90.6%
Pima 980,977 1,442,420 47.0% 2,131,150 47.7%
Cochise 134,789 187,725 39.3% 265,388 41.4%
Graham 35,873 44,556 24.2% 62,261 39.7%
Source: Arizona Department of Economic Security for 2006, 2030
Maricopa Association of Governments for 2050
Other studies however, such as the Pinal County Small Area Transportation Study prepared in
2006, estimates the population in Pinal County could be as high as 1,954,016 by 2030. The
Morrison Institute in The Future of Pinal, Making Choices, Making Places indicates that there
are already 650,000 “entitled” housing units in Pinal County, and the county population could be
1,302,950 by 2050. It does appear likely that in the next two or three decades, the population of
Pinal County will be greater than the current population of Pima County. Much of this
population will be centered between the Phoenix and Tucson metropolitan areas and will create
another major urban hub.
The Southeast Arizona Regional Transportation Profile estimates future population in Benson of
78,210 and 19,094 in Willcox. Through a conversation with Graham County staff, they indicated
population projections as high as 100,000 residents in the Safford area.
Figure 1.1 presents a vision of population growth for the State of Arizona as developed by MAG
for 2050. The plan identifies the Arizona Sun Corridor Megapolitan area with the population
concentration reaching from the Prescott area to the Phoenix metropolitan area to the Tucson
metropolitan area to Sierra Vista. This graphic again emphasizes that central Pinal County will
likely greatly exceed what Tucson is today.
Figure 1.1
Arizona Future Growth
I -10 Phoenix-Tucson Bypass Sttudy
Data Source: Maricopa Association of Governments
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1.5 PURPOSE AND NEED
Early in the study process, a purpose and need statement was developed for review by the TAC
at the April meeting. Refinements to the statement were made, and it was shown to the public in
the first round of public meetings and to the stakeholders during the interview process.
The statement shown below is based upon the general need as identified initially by the State
Transportation Board and refined by the study team.
Purpose
• To provide an additional high-capacity transportation corridor to accommodate travel
across southern and central Arizona.
Need
• Provide alternative route to I-10 to relieve traffic congestion on I-10 in the Phoenix and
Tucson metropolitan areas.
• Provide a shorter, faster route through southern and central Arizona that will attract
through trucks and other traffic from I-10.
• Provide a new route that offers an alternative path for I-10 traffic during construction,
maintenance, and incidents.
• Provide a new transportation corridor to serve the expected rapid population growth and
land development in the Sun Corridor.
• Develop a corridor that is context sensitive to environmental and social elements.
If study of this corridor proceeds to the next level of project development, the purpose and need
statement should be refined and more specific needs identified based in part on the findings
included in this report.
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2.0 I-10 EXISTING AND FUTURE CONDITIONS
2.1 EXISTING CONDITIONS
The existing I-10 corridor is one of the major cross-country Interstate routes, serving traffic from
Florida to Los Angeles. The construction of I-10 replaced or used alignments of existing US and
State Highways (US 60, AZ 85, AZ 84, and AZ 86). A section of old US 80 (now I-10) southeast
of Tucson was the first project in Arizona under the Federal Interstate Highway Act. I-10 was
completed through Phoenix in 1990. I-10 provides the main interstate east-west corridor through
Arizona connecting California and New Mexico and serving the bulk of the population and
economic base in Arizona.
The segment of I-10 that is the subject of this study begins west of the junction with SR 85 at
milepost (MP) 98. From there eastward, the route continues through the Phoenix Metropolitan
Area and then takes a southeastward alignment to pass through the Gila River Indian
Community, the communities of Casa Grande, Eloy, and Marana and passes through the Tucson
Metropolitan Area. Continuing eastward, the corridor leads through the City of Benson. The
study corridor terminates east of the City of Willcox at the junction with US 191-MP 356. The
I-10 corridor is approximately 258 miles in length and provides mobility on an interstate, intra-state,
small urban and large urban scale. Based on the wide variety of built, agricultural, and
natural environment, the characteristic and function of the corridor vary widely.
Table 2-1 presents an overview of the existing number of lanes (based on the 2005 Highway
Performance Monitoring System [HPMS] data set). The existing number of lanes vary from
4 through lanes in primarily rural areas to sections with 10 and 12 lanes within the Phoenix
Metropolitan Area. Similarly, existing traffic volumes range from about 25,000 vehicles per day
(vpd) west of SR 85 to almost 300,000 vpd in the Phoenix Metropolitan Area. Traffic volumes
reduce to about 40,000 vpd at the intersection with Interstate 8 (I-8) near Casa Grande and
increase to about 160,000 vpd in Tucson. At the east end of the corridor, approximately
14,000 vpd are recorded.
Figure 2.1 illustrates the traffic volumes and truck percentages in the study corridor. In rural
areas, trucks account for up to 45 percent of traffic volumes while within the metropolitan areas
truck percentages are much lower due to the overall high traffic volumes. The recently available
2006 traffic counts were reviewed and compared to 2005 counts. For the most part, there was an
increase in volumes in most places. Due to daily fluctuations in traffic, counts need to be
compared over several years to establish trends.
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Table 2-1 I-10 2005 Average Daily Traffic and Number of Through Lanes
Milepost West of Cross Road
2005
Through
Lanes
Existing
Volume
(2005)
Existing
Truck %
103.45 SR 85 4 25,000 36%
124.5 Loop 303 4 72,000 29%
132.12 Dysart Road 4 176,000 15%
134.03 Loop 101 6 123,000 28%
136.70 75th Avenue 10 137,000 11%
144.7 7th Avenue 12 281,000 11%
145.7 7th Street 10 285,000 11%
146.96 SR 51 12 285,000 11%
148.9 Buckeye Road 8 230,000 11%
150.01 24th Street 12 296,000 11%
151.47 University Drive 10 291,000 11%
155.83 US 60 10 206,000 11%
157.77 Elliot Road 8 152,000 35%
161.10 Chandler Boulevard 6 91,000 35%
161.2 Loop 202 6 91,000 35%
164.5 Queen Creek Road 4 87,000 35%
169 Riggs Road 4 47,000 35%
199.16 I-8 4 37,000 34%
240.74 Tangerine Road 6 48,000 38%
247.25 Cortaro Road 4 82,000 38%
260.39 I-19 6 156,000 21%
268.7 Craycroft Road 6 49,100 21%
270.87 Kolb Road 4 53,000 17%
302.7 SR 90 4 25,400 45%
352.2 US 191 4 14,000 45%
Source: ADOT Highway Log, 2005 HPMS
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Figure 2.1 2004 Traffic Volumes and Truck Percentage
2.2 PLANS FOR IMPROVING I-10
Indicative of the high development pressure and the associated mobility needs within the study
corridor, a multitude of transportation studies were recently completed, are currently under way,
or are planned to start in the near future. Appendix A provides a list and summary of relevant
studies.
Local Transportation Studies: Studies such as Small Area Transportation Studies (SATS) help
local jurisdictions define transportation needs and systems ranging from individual cities and
towns to county-wide efforts such as the Pinal County SATS. In most cases, a SATS establishes
travel demand forecasts for the area under study.
Regional Studies: On a regional scale, ADOT uses a variety of study formats to examine the
needs and deficiencies on the State Highway System. These studies may encompass multiple
counties and jurisdictions. One example is the currently ongoing Southern Pinal/Northern Pima
Corridor Definition Study that will establish a list of prioritized highway projects for the area
between the Phoenix and Tucson metropolitan areas. Next to establishing future forecasts, the
study will also look at the possibility of additional capacity needs besides what can be
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accomplished through improvements to the existing State Highway System. New high capacity
corridors will be identified.
Identification of new corridors in the metropolitan areas is also undertaken by the respective
metropolitan planning organizations (MPOs). MAG recently initiated a series of “Regional
Framework studies” such as the I-10 Hassayampa and Hidden Valley framework studies that
look beyond the traditional 20-year planning horizon identifying needed high-level facilities
based on build-out forecasting. The Pima Association of Governments (PAG) is in the process of
concluding the PAG Loop Road Study assessing the potential for freeway facilities in the Tucson
area. The MPOs are also sources of travel-related statistics and forecasts such as the MAG:
Phoenix External Travel Survey (2001) and the 2006 Freeway Level of Service Study.
Statewide Studies: Several studies are currently under way that examine multi-modal mobility
needs. URS is preparing the Commuter Rail Study for MAG and is a part of the team that
provided an update of a study of High-Speed Rail between Phoenix and Tucson. Wilbur Smith
Associates (WSA) will be starting the Arizona Freight Study. ADOT has recently launched a
major effort to to update the 2005 MoveAZ Statewide Transportation Plan.
National and Other Pertinent Studies: The national I-10 Freight Study (conducted by WSA)
analyzed the multi-modal transportation needs for I-10 and developed a plan for improvements
to the interstate corridor.
Corridor Specific Studies: In addition, ADOT undertook a series of corridor specific studies
such as the Pinal County Corridor Definition Studies evaluating the need for additional high-capacity
corridors in Northern Pinal County. ADOT is also conducting a series of corridor
studies on I-10 as described below:
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I-10 Corridor Study: SR 51/Piestewa to Loop 202/Santan Freeway Corridor Improvement
Study
A Corridor Improvement Study (CIS) is currently under
way to evaluate freeway improvement alternatives along
I-10 from SR 51 to Loop 202. Alternatives being evalu-ated
include the addition of local and express access routes
in the study area. Preliminary findings call for up to
24 lanes in sections of the study corridor.
I-10 Corridor Study: I-8 to Loop 202 Corridor Study
The I-10/I-8 to Loop 202 Corridor Study is just getting
under way and will examine deficiencies and needs for the
I-10 corridor between Casa Grande and Chandler. One
issue the study will discuss is I-10 location on a perpetual
easement through the Gila River Indian Community. The
easement is defined in a lease agreement between the Gila
River Indian Community, ADOT, the Bureau of Indian
Affairs (BIA), and Federal Highway Administration dated
1966. The lease agreement included concepts for the
roadway cross-section that will be discussed among the
stakeholders and will be evaluated in the upcoming
corridor study. One issue is that some of the concepts developed in 1966 are not in compliance
with current roadway design standards. One of the objectives of the study is to analyze an
interim widening of I-10 and will look at the feasibility to continue the cross-section defined in
the I-10 Corridor Study I-8 to Tangerine Road with 10 lanes with two frontage roads from I-8 to
Loop 202. The study will rely on travel demand modeling from MAG and has requested model
assignments.
I-10 Corridor Study: Tangerine to I-8 Corridor Study
The I-10 Tangerine to I-8 corridor study is studying long-term improvements for 41 miles of
I-10, between I-8 at MP 199 in Casa Grande and Tangerine Road at MP 240 in Marana. The
study determined an ultimate cross-section of 10 lanes with two-lane frontage roads by 2030. A
total right-of-way of between 430 and 500 feet will be needed to accommodate the facility. The
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study effort developed a travel demand forecast for the I-10 corridor. Results of the forecast
indicate that travel demand will far exceed what can be accommodated by the improved I-10
corridor. In sections north of Tucson, more than 400,000 vpd are forecasted. Capacity for excess
demand is assumed to be provided by additional facilities such as the potential Phoenix-Tucson
bypass.
Since future traffic volumes are expected to exceed the current capacity of the I-8/I-10
interchange, the development of a long-range plan (2030) for the I-8 interchange area has been
added to the I-10 corridor study.
I-10 Corridor Study: I-19 to the Pima/Cochise County Line
The purpose of the I-10 Corridor Study is to identify transportation needs and transportation
deficiencies and to develop recommendations for corridor rehabilitation to meet multimodal
transportation demands in the year 2030 along approximately 37 miles of I-10 from I-19 to the
Pima/Cochise County line. The I-10 Corridor Study involves the development of planning
studies, engineering analyses, an environmental overview, and planning-level transportation
road-way design. Study recommendations are intended for use by ADOT to program interstate
rehabilitation, preserve right-of-way, manage corridor land uses, and protect access control.
Summary of Currently Proposed Lanes on I-10
Table 2-2 presents an estimate of planned number of lanes as identified by the various regional
travel demand models and corridor specific models.
Table 2-2 Estimate of Planned Number of Lanes and 2030 Model Volumes
Milepost West of Cross Road
2030 AADT
(000’s)
2030
Lanes Agency/Study
113.0 SR 85 128 6 MAG
124.5 Loop 303 164 6 MAG
132.12 Dysart Road 232 10 MAG
134.03 Loop 101 280 12 MAG
136.70 75th Avenue 280 12 MAG
144.7 7th Avenue 296 12 MAG
145.7 7th Street 341 10 MAG
146.96 SR 51 340 12 MAG
148.9 Buckeye Road 186 8 MAG
150.01 24th Street 326 12 MAG
151.47 University Drive 412 17 MAG
155.83 US 60 427 22 MAG
157.77 Elliot Road 247 10 MAG
161.10 Chandler Boulevard 196 10 MAG
161.2 Loop 202 195 10 MAG
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Milepost West of Cross Road
2030 AADT
(000’s)
2030
Lanes Agency/Study
164.5 Queen Creek Road 127 8 MAG
169 Riggs Road 123 6/ Pinal SATS/
8 MAG
199.16 I-8 104 10 I-10 DCR
6 Pinal SATS
4 MAG
240.74 Cortaro Road N/A 10 I-10 DCR
6 Pinal SATS
247.25 Tangerine Road 415 10 I-10 Design Concept
Report (DCR)
160 8 PAG
260.39 I-19 198 8 PAG
265.3 Alvernon Way 95 8 I-10 Southeast CS/ PAG
270.87 Kolb Road 100 10 I-10 Southeast CS/ PAG
275.7 Houghton Road 100 8 I-10 Southeast CS/ PAG
302.7 SR 90 N/A 6 I-10 Southeast CS/ PAG
352.2 US 191 N/A 4
Programmed Projects
ADOT has programmed the following projects within the Phoenix Area. The lanes added are for
each direction of travel.
• Verrado Way to Sarival Avenue: Add one general purpose lane in median
• Sarival Avenue to Dysart Road: Add high-occupancy vehicle (HOV) lane and two
general purpose lanes
• Dysart Road to Loop 101: Add HOV and one general purpose lane
• Loop 101 to I-17 – Phase 1: Add general purpose lane
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Figure 2.2 MAG I-10 Improvements
ADOT has identified four interim improvement project to widen I-10 between Tangerine Road
and I-8 to three lanes in each direction and construction is expected to start in 2008. The four
sections are: I-8 to SR 87, SR 87 to Picacho Peak Road, Picacho Peak Road to Pinal Air Park,
and Pinal Air Park to Tangerine Road.
2.3 PLANS FOR IMPROVEMENTS TO OTHER HIGHWAYS
2.3.1 US 70
Approaching Arizona from New Mexico on I-10, an alternative route is US 70 from Lordsburg
to Globe and US 60 from Globe to Phoenix. Substantial improvements to US 70 could make this
a viable alternate route from Lordsburg to the Phoenix metropolitan area. For the most part,
US 70 is a two-lane rural highway and would require widening and major improvements.
Portions of the route traverse rugged terrain; other portions are located within the San Carlos
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Indian Reservation. Generally, this alternative route could serve as a bypass of Tucson for traffic
destined between New Mexico and Phoenix or northern Arizona. In recent years, US 70 was
widened to a five-lane urban cross-section through the communities of Pima, Thatcher, and
Safford. In addition, ADOT is currently improving the Gila River Bridge at Bylas on US 70.
ADOT is also studying a potential realignment of US 191 and US 70 in the Safford area.
2.3.2 US 60
ADOT has completed preliminary feasibility studies for substantial improvement to US 60
between Superior and Globe through the rugged mountainous and mining area. Design concept
and environmental studies will begin later this year. The highway is currently operating at a poor
level of service (LOS), and crashes occur at a high rate and severity. US 60 serves as a critical
link between the Phoenix Metropolitan Area and the east-central portions of Arizona, providing
access to several national forest recreation areas and the White Mountain Apache Indian
Reservation. The highway also serves as a commercial link to several towns and communities
including Superior and the Globe-Miami area. US 60 also connects to US 70 east of Globe,
which leads to Safford and could serve as an alternate route for I-10 traffic from Lordsburg to
Phoenix, bypassing Tucson. However, several of the preliminary alternatives for the study focus
on bypassing the Miami-Globe area to the north favoring connectivity of the US 60 route. If this
occurs, direct connectivity of the US 60 to US 70 would be diminished.
2.3.3 US 191
ADOT has widened a substantial portion of US 191 between I-10 and US 70 in Safford to a four-lane
divided highway. Portions currently remain as a two-lane rural highway. ADOT is
completing the design to widen US 191 between MP 91.80 and MP 94.34, just north of I-10.
Design concept and environmental studies are under way to complete the widening and possible
realignment of US 191 through the south Safford area to connect with US 70.
2.3.4 I-8
Currently there are no plans for improvements to the I-8 corridor. Pinal County suggests that I-8
be planned for 10 lanes and frontage roads and is requesting developers preserve the right-of-way.
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2.3.5 SR 85
Together with I-8, SR 85 is the official truck bypass route around metropolitan Phoenix and has
also been designated as the CANAMEX corridor as part of the North American Free Trade
Agreement (NAFTA). In addition to serving as the I-10 bypass, this corridor also metropolitan
Phoenix to I-8 which leads to Yuma and San Diego. An ADOT DCR and subsequent Access
Management Study identified 12 interim corridor segments that ultimately will construct two
additional lanes to provide a continuous four-lane divided highway from I-8 in Gila Bend to I-10
in Buckeye. These interim corridor segment improvements make up the first phase toward the
ultimate goal of a fully access controlled highway. Construction of all sections, except the bypass
of Gila Bend, is expected to be completed by 2010.
ADOT is currently preparing a DCR for a fully access controlled-facility that will connect SR 85
to I-8 near Gila Bend. No alternative has been selected yet. The study is currently evaluating
feasible alternatives for this connection.
2.3.6 South Mountain Freeway
The planned South Mountain Freeway would extend SR 202L from I-10 near Pecos Road
westward around South Mountain and reconnect with I-10 in the vicinity of 51st Avenue. This
project is included in the MAG RTP and in the Proposition 400 funding program. An
Environmental Impact Statement (EIS) is being prepared. Funding is included in Phases I and II
of the MAG plan. Completion of this roadway would offer an alternative route to I-10 for the
most congested portion in Phoenix and Tempe.
2.3.7 I-10 Reliever
SR 801, also known as the I-10 Reliever, is a planned state highway in the southwest portion of
the Phoenix metropolitan area. It will connect the southern terminus of Loop 303 with the South
Mountain leg of Loop 202. It is planned as a controlled-access freeway to relieve heavy traffic
congestion experienced along I-10 in the area. Although no construction has begun for the route,
planning documents have identified a study area running roughly 5 miles south of and parallel to
I-10 through largely undeveloped land. In addition to reducing commuter traffic on I-10, SR 801
will serve the industrial and warehouse district in southwest Phoenix, and particularly the truck
traffic generated by this district.
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2.4 OTHER MODES
2007 Review of the 1998 Arizona High-Speed Rail Study
ADOT undertook a review of the 1998 Arizona High-Speed Rail Study, assessing rail options in
the Phoenix-Tucson Corridor. The 1998 study forecasted 2020 daily traffic of 51,000 vehicles on
I-10 near the I-8 interchange. Of the total number of vehicles, 25 percent was estimated to be
commercial vehicles. The study contained four alternatives for high-speed rail which varied in
speed and costs. The four alternatives are:
• Alternative 1, Conventional Rail – Minor Upgrade
• Alternative 2, Conventional Rail – Major Upgrade
• Alternative 3, High-Speed Rail – Electric
• Alternative 4, High-Speed Rail – Magnetic Levitation
The 1998 study contained a reduction of daily travel on I-10 of 2,750 vehicles for Alternative 1,
5,300 vehicles for Alternative 2, 6,000 vehicles for Alternative 3, and 6,500 vehicles for
Alternative 4. This equates to reductions ranging from 5 percent to 13 percent of the 2020 daily
traffic on I-10.
In the 2007 update, the 2020 projection of traffic on I-10 was increased to 58,000 vpd. The
projection of the percentage of commercial vehicles was also increased to 37 percent of the total
traffic per ADOT provided data. The higher truck percentage indicates that truck traffic is
expected to increase faster than all traffic. The 2007 report concluded that the 1998 study high-speed
rail usage estimates appear to provide a reasonable order of magnitude.
Commuter Rail Strategic Plan
MAG is conducting the Commuter Rail Strategic Plan (CRSP) for Maricopa County and
northern Pinal County. The MAG 2003 High Capacity Transit Study provides a strong
foundation for the Strategic Plan. Goals of the study are to:
• Assess local and regional support for commuter rail
• Identify and evaluate issues related to implementation, such as funding, governance and
administration, environmental issues, land use and sprawl, capacity constraints, and other
issues
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• Develop a methodology for evaluating potential commuter rail corridors
• Establish and gain consensus for an implementation strategy and plan
2.5 2030 TRAFFIC FORECASTS
Based on existing studies and forecasts, most of the existing and future roadways and freeways
in the Phoenix and Tucson metropolitan areas will not be able to provide sufficient capacity to
accommodate future travel demand. Similarly, if growth trends continue, much of central Pinal
County will be underserved by major transportation routes. As outlined in Table 2-2 of Estimate
of Planned Number of Lanes and 2030 Model Volumes, 2030 traffic volumes on I-10 in the
Phoenix Area are projected to exceed 400,000 vpd even with all the Proposition 400 projects in
place at that time. Similarly, existing I-10 in Tucson will approach 200,000 vpd with currently
planned improvements in place. Traffic forecasts for the I-10 segment between Tucson and
Phoenix vary considerably among studies and forecasts. The forecasts developed as part of this
study estimate approximately 100,000 vpd on I-10 between the two major metropolitan areas.
As part of this I-10 Bypass Study traffic forecasts were made and are described in more detail in
Chapter 5 and in a technical memorandum included in the Appendix. Table 5-1 provides a
summary of the forecast. The overall bypass corridor was divided into the west segment and the
east segment. There are two alternatives for the east segment one that would go north of Tucson
and intersect I-10 near Willcox and the other that would go west and south of Tucson and
intersect I-10 near SR 83 east of Tucson.
The three corridor concepts were tested to identify the relief they would provide on the I-10
corridor as well as how much traffic they would carry. The traffic forecast on the bypass corridor
consists of long-trips and through traffic only. Traffic that may be generated by urban
development that may occur along the corridor is not included in the estimate.
The West Segment could potentially carry at least 53,000 vpd in 2030 and relieve the existing
I-10 in the Phoenix area by more than 44,000 vpd. The I-10 East Segment (west and south of
Tucson) would carry over 39,000 vpd in 2030, relieving traffic on I-10 through the Tucson area
by almost 33,000 vpd. The East Segment (north of Tucson) would be used by at least 17,500 vpd
in 2030 resulting in a potential decrease of 14,500 vpd on I-10 in the Tucson Area. If both the
East Segment options are constructed, the reduction in traffic on I-10 in Tucson would be
40,000 vpd in 2030.
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2.6 NEED FOR BYPASS
The foregoing information provides a basis to make a preliminary assessment of the need for a
new corridor that would serve as a bypass for I-10 in the Phoenix and Tucson metropolitan areas.
I-10 in Phoenix is congested today, and ADOT has programmed several projects that will add
lanes to I-10 through the entire metropolitan area. Construction on some of the widening is
scheduled to begin later in 2007. In addition, the MAG RTP includes the South Mountain
Freeway and SR 801 (I-10 Reliever) and Proposition 400 provides some of the funding needed
for these new routes. The two new routes are designed to offer relief and alternative routes to
I-10 in the Phoenix area; however, the 2030 forecast prepared by MAG indicates that even with
these additional routes and light-rail transit, I-10 is expected to carry the maximum load possible
which means there will be peak-hour congestion. Peak-hour congestion seems inevitable in a
metropolitan area of 6 million people.
SR 85 and I-8 is the designated I-10 bypass route for the Phoenix metropolitan area. When SR 85
is completed as a four-lane access controlled highway, this bypass route should serve this
function for many years to come. Urban growth expected in the Tonopah Valley-Buckeye-
Goodyear-Maricopa area will not be served well by SR 85 and I-8 because the Sonoran Desert
National Monument separates the potential urban development from these routes. Accordingly,
additional routes may be needed to serve the future urban growth in the area.
The SR 85/I-8 bypass is slightly longer than staying on I-10 (approximately 5 miles longer).
When SR 85 is completed, it will provide a route where constant high speeds can be maintained
so that it will serve well as a bypass route for several years.
I-10 in Tucson will be widened to provide four lanes in each direction. Additional widening is
not likely because of the major impacts that would occur to adjacent land uses. The projected
2030 traffic volumes of up to 200,000 vpd indicate that peak-hour congestion will be the norm in
Tucson.
I-10 is the only east-west route that passes through southern Arizona. US 191-US 70-US 60
offers an alternative route for traffic entering Arizona from New Mexico and wanting to go to
Phoenix. Improvements to US 70 through the San Carlos Apache Indian Reservation are not
likely to occur. US 60 is limited as a truck route because it passes through very rugged
mountainous terrain. Since this route connects into the freeway system in the greater Phoenix
area, it would not serve interstate (New Mexico to California) traffic very well.
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Given the expected worsening traffic congestion in Tucson and the absence of a suitable
alternative route, there appears to be a need to further consider bypass alternatives for I-10 in
southern Arizona.
The dramatic growth in truck traffic in Arizona and throughout the nation has created a major
challenge to the nation’s highway system. Similarly, the growth in rail freight has overwhelmed
the railroad industry. Union Pacific Railroad (UPRR), which roughly parallels I-10 and I-8
through Arizona, is undergoing major upgrades to provide double tracks from El Paso to Los
Angeles. A major new rail yard is currently planned near I-10 in southern Pinal County. Even
with the improvements to the rail system, substantial increases in truck traffic appear likely. The
percentage of the total number of vehicles on I-10 that are heavy trucks (outside the two major
metropolitan areas) is already 30 to 50 percent and could go higher.
With the expected urban growth in central Pinal County, I-10 will essentially become an urban
freeway from west of SR 85 to east of Tucson. This means that interstate traffic on I-10
(including many trucks) will be subjected to the typical urban peak-hour congestion for
150 miles in Arizona. This situation would cost everyone hundreds of dollars per year in lost
time and increased cost of goods and services due to increased travel time. The total reliance on
one major route through southern Arizona places a huge risk that a crash, construction, or major
event could shut down the main lifeline to 80 percent of the population in Arizona.
Final Report
I-10 Phoenix-Tucson Bypass Study
Arizona Department of Transportation
3-1
January 2008
URS Job No. 23445042
P:\TRANSPORTATION\ADOT_TPD\23445042_I-10_Phx_Tucson_Bypass_Study\Docs\Final Reports\Final Report\I-10 Bypass Study Final Report 01-2008.doc
3.0 POTENTIAL NEW CORRIDORS
3.1 INITIAL POTENTIAL CORRIDOR ALTERNATIVES
In January 2007, an article appeared in the Tucson Citizen regarding the need for an I-10
Phoenix-Tucson bypass. That article contained a graphic that showed a potential corridor starting
at I-10 west of SR 85 and running generally southeastward and crossing I-8 west of Casa Grande
and crossing I-10 in Pinal County south of the I-8 junction. The corridor continued eastward and
then southeastward in the San Pedro Valley to rejoin I-10 at one of several potential connection
points between Willcox and Benson. This initial corridor illustrated the basic concept as
envisioned by the State Transportation Board when the study was initiated. This basic corridor
idea was included in the Request for Proposals issued by the Transportation Planning Division.
From this initial idea, several other initial potential corridors were identified. These ideas were
presented to the TAC on April 25, 2007, for concurrence that they were suitable to show to the
public and stakeholders in the series of meetings and interviews conducted in May and June.
This initial set of corridors did provide a basis for the public and stakeholders to understand the
scope and intent of the bypass and to provide more specific reaction to the various ideas.
In order to develop the initial potential corridors, the major fatal flaw constraints were identified
through existing geographic information system (GIS) databases. Four constraints maps were
prepared as shown in Figure 3.1 through Figure 3.4. The first shows major environmental
constraints including preserved lands (National forests, monuments, parks, wilderness areas;
areas of critical environmental concerns, faults, rivers, Central Arizona Project [CAP] Canal).
These data have been refined during the course of this study.
The potential corridors were laid out to avoid the preserved areas and to minimize crossings of
other highways, streams and railroads. These data were refined during the course of the study.
The second figure shows land ownership (or the agency that manages the surface of the land).
Indian Reservation Land was avoided. Bureau of Land Management (BLM) land was avoided
where possible. State Trust Lands are for future development so they were viewed as
opportunities for potential location of a new corridor. The third figure shows the major
topographic features. Most of these features coincide with the preserved land identified in
Figure 3.1. Figure 3.4 shows the major existing highways and railroads to provide a basis for
looking at what connections may be made with a new potential future corridor.
South
Maricopa Mtns.
Wilderness
Table Top
Wilderness
Sonoran Desert
National Monument
Picacho Peak
State Park
Ironwood Forest
National Monument
Coyote Mtns.
Wilderness
Baboquivari
Peak
Wilderness
San Pedro Valley
West Saguaro
Wilderness
Saguaro National
Park
Catalina
State
Park
Pusch
Ridge
Wilderness
Oracle
State
Park
Aravaipa
Canyon
Wilderness
Santa Teresa
Wilderness
North Santa Teresa
Wilderness
Galiuro
Wilderness
Dos Cabezas
Mountains
Wilderness
Saguaro National
Park Rincon
Mountain District
East
Saguaro
Wilderness
Rincon
Mountain
Wilderness
North
Maricopa Mtns.
Wilderness
Big Horn Mountains
Wilderness
Tonto National Forest
Woolsey Peak
Wilderness
Sierra Estrella
Wilderness
Superstition
Wilderness
Kartchner
Caverns
State Park
Chiricahua
Wilderness
Fishooks
Wilderness
Organ Pipe
National Monument
and Wilderness
Cabeza Prieta
National
Wildlife
Refuge
and
Wilderness
Blue Ridge
Primitive
Wilderness
Aravaipa Valley
Casa Grande
National Monument
Coronado
National
Forest
Coronado
National
Forest
Coronado
National
Forest Hot Springs Canyon
Copper Creek
Cooks Lake
Three Links Farm
Pinaleno
Mountains
Willcox
Playa
Winchester
Mountains Sulphur
Springs
Valley
Allen
Flat
Proposed
Park
Cactus
Forest
Tortolita
Mountain
Park
Avra
Valley
Buehman
Wet Lands
Proposed
Park
White Tanks Mountains
Regional Park
South Mountain
Park
Palo Verde
Mountains
Haley Hills
Santan Mountains
Regional Park
Pima County
Fair Grounds
Coronado
National Forest
Coronado
National Forest
Fort Bowie
National
Historic Site
Peloncillo Mountains
Wilderness
Gila Box Riparian
National Conservation
Area
Bear Springs
Badlands
Needles Eye
Wilderness
Coffee Pot
Ajo Regional Mountain
Park
Desert
Grasslands
Tucson
Mountain
Park
Tucson Mitigation
Corridor
TUCSON
BENSON
WILLCOX
SAFFORD
MARANA
ELOY
CASA GRANDE
COOLIDGE
FLORENCE
GLOBE
MARICOPA
GILA BEND
PHOENIX
MESA
BUCKEYE
GOODYEAR
TOHONO O'ODHAM NATION
SAN CARLOS APACHE
INDIAN RESERVATION
SAN XAVIER
Santa Cruz River
San Pedro River
Gila River
Gila River
Santa Cruz River
Salt River
Gila River
CAP CANAL
SUPERIOR
Legend
Study Area
CAP Canal
Major Rivers
City Limits
Area of Critical Environmental Concern
Wilderness Areas
National Monuments
Forest / Parklands / Other Conservation Areas
Figure 3.1
Environmental Constraints
II--10 Phoeniix--Tucson Bypass Sttudy
Data Source: ALRIS 1997 - 2005, Bureau of Land Management, ADOT ATIS 2005, ADOT HPMS 2005, USGS, Bureau of Transportation Statistics
0 2.5 5 10 15 20
Miles
Scale Data Source: ALRIS 1997 - 2005, Bureau of Land Management,
ADOT ATIS 2005, ADOT HPMS 2005, USGS,
Bureau of Transportation Statistics
P:\TRANSPORTATION\ADOT_TPD\23445042_I-10_Phx_Tucson_Bypass_Study\Docs\Final Reports\Figures\Fig3_1_Envi_Constraints.pdf (ai)
Disclaimer:
While every effort has been made to ensure the accuracy
of this information, the Arizona Department of Transportation
makes no warranty, expressed or implied as to its accuracy
and expressly disclaims liability for the accuracy thereof.
Figure 3.2
Land Ownership
TUCSON
BENSON
WILLCOX
SAFFORD
MARANA
ORO VALLEY
ELOY
CASA GRANDE
COOLIDGE
FLORENCE
GLOBE
MARICOPA
GILA BEND
PHOENIX
MESA
BUCKEYE
GOODYEAR
TOHONO O'ODHAM NATION
SAN CARLOS APACHE
INDIAN RESERVATION
SAN XAVIER
WHITE MOUNTAIN APACHE
Legend
BLM
U.S. Forest Service
National Park Service
USFWS National Wildlife Refuge
American Indian Res.
Military
State Trust
Local or State Parks
Other; Private
City Limits
I -10 Phoenix-Tucson Bypass Sttudy
Data Source: ALRIS 1997 - 2005, Bureau of Land Management, ADOT ATIS 2005, ADOT HPMS 2005, USGS, Bureau of Transportation Statistics
0 2.5 5 10 15 20
Miles
Scale Data Source: ALRIS 1997 - 2005, Bureau of Land Management,
ADOT ATIS 2005, ADOT HPMS 2005, USGS,
Bureau of Transportation Statistics
P:\TRANSPORTATION\ADOT_TPD\23445042_I-10_Phx_Tucson_Bypass_Study\Docs\Final Reports\Figures\Fig3.2_LandOwnership.pdf (ai)
Disclaimer:
While every effort has been made to ensure the accuracy
of this information, the Arizona Department of Transportation
makes no warranty, expressed or implied as to its accuracy
and expressly disclaims liability for the accuracy thereof.
TUCSON
BENSON
WILLCOX
SAFFORD
MARANA
ORO VALLEY
ELOY
CASA GRANDE
COOLIDGE
FLORENCE
GLOBE
MARICOPA
GILA BEND
PHOENIX
MESA
BUCKEYE
GOODYEAR
TOHONO O'ODHAM NATION
SAN CARLOS APACHE
INDIAN RESERVATION
SAN XAVIER
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Figure 3.3
Topography
Legend
I -10 Phoenix-Tucson Bypass Sttudy
Data Source: ALRIS 1997 - 2005, Bureau of Land Management, ADOT ATIS 2005, ADOT HPMS 2005, USGS, Bureau of Transportation Statistics
0 2.5 5 10 15 20
Miles
Scale Data Source: ALRIS 1997 - 2005, Bureau of Land Management,
ADOT ATIS 2005, ADOT HPMS 2005, USGS,
Bureau of Transportation Statistics
P:\TRANSPORTATION\ADOT_TPD\23445042_I-10_Phx_Tucson_Bypass_Study\Docs\Final Reports\Figures\Fig3.3_Topography.pdf (ai)
Shaded Relief
Contour Line (1,000' Interval)
Major Roads
City Limits
0 - 1,000 ft
1,000 - 2,600 ft
2,600 - 4,200 ft
4,200 - 5,500 ft
5,500 - 6,800 ft
6,800 - 12,598 ft
Disclaimer:
While every effort has been made to ensure the accuracy
of this information, the Arizona Department of Transportation
makes no warranty, expressed or implied as to its accuracy
and expressly disclaims liability for the accuracy thereof.
TUCSON
BENSON
WILLCOX
SAFFORD
MARANA ORO VALLEY
ELOY
CASA GRANDE
COOLIDGE
FLORENCE
GLOBE / MIAMI
GILA BEND
PHOENIX
MESA
BUCKEYE
GOODYEAR
TOHONO O'ODHAM NATION
SAN CARLOS APACHE
INDIAN RESERVATION
SAN XAVIER
PIMA
COCHISE
GRAHAM
PINAL
GILA
MARICOPA
GREENLEE
APACHE
Union Pacific RR
Cooper Basin RY
Arizona Eastern Railway
Union Pacific RR
Union Pacific RR
San Manuel
Arizona RR
Tucson-Cornelia &
Gila Bend RR
SELLS
RYAN FIELD
TUCSON INTL
BENSON MUNICIPAL
SAN MANUEL
PINAL AIRPARK
MARANA REGIONAL
KEARNY
ELOY MUNI
CASA GRANDE MUNI
PHOENIX REGIONAL
GILA BEND MUNI
CHANDLER MUNI
PHOENIX SKY HARBOR INTL
LOST DUTCHMAN
SAN CARLOS APACHE
BUCKEYE MUNI
PHOENIX GOODYEAR
SAFFORD REGIONAL
AJO MUNI
SUPERIOR MUNI
FALCON FIELD
GLENDALE
Figure 3.4
Existing Transportation System
Legend
I -10 Phoenix-Tucson Bypass Sttudy
Data Source: ALRIS 1997 - 2005, Bureau of Land Management, ADOT ATIS 2005, ADOT HPMS 2005, USGS, Bureau of Transportation Statistics
0 2.5 5 10 15 20
Miles
Scale Data Source: ALRIS 1997 - 2005, Bureau of Land Management,
ADOT ATIS 2005, ADOT HPMS 2005, USGS,
Bureau of Transportation Statistics
P:\TRANSPORTATION\ADOT_TPD\23445042_I-10_Phx_Tucson_Bypass_Study\Docs\Final Reports\Figures\Fig3.4_Transportation.pdf (ai)
Railroads
Major Roadways
Local Roads
City Limits
Airports
Disclaimer:
While every effort has been made to ensure the accuracy
of this information, the Arizona Department of Transportation
makes no warranty, expressed or implied as to its accuracy
and expressly disclaims liability for the accuracy thereof.
Final Report
I-10 Phoenix-Tucson Bypass Study
Arizona Department of Transportation
3-6
January 2008
URS Job No. 23445042
P:\TRANSPORTATION\ADOT_TPD\23445042_I-10_Phx_Tucson_Bypass_Study\Docs\Final Reports\Final Report\I-10 Bypass Study Final Report 01-2008.doc
The initial set of potential corridor alternatives is shown in Figure 3.5. This graphic was
presented in the public meetings held in May and was shown to the stakeholders during the
interviews. The alternatives included existing highways that do or could serve as an alternative to
I-10, planned/proposed freeway corridors from the MAG, CAAG, and PAG planning processes,
and corridors that someone had suggested or that the project team thought had merit based upon
a quick review of various major constraints features that were identified from the available
statewide GIS data sources.
During May and June, the project staff interviewed staffs of 28 stakeholder agencies. These
stakeholders included most of the cities and counties that might be affected by the potential
bypass and many special purpose groups and organizations that expressed interest in the project.
The Arizona State Land Department and the Arizona Game and Fish Department were
interviewed as well. The interview process is described more fully in Chapter 8.
The response from the individual stakeholder agencies is shown in Table 3-1 and combined in
Table 3-2. In general the stakeholders indicated support for the bypass idea and specifically for
initial potential corridor alternatives C, F/M, and H. In general most of the cities and counties
expressed support for the bypass. Most of the specialized environmental organizations oppose
the bypass with strong opposition to corridor K. In this summary, corridor K is used to represent
all alternatives in the San Pedro Valley. Other stakeholders expressed support for corridors C, H,
K, and M.
Tohono O'odham Nation
San Carlos Apache
Indian Reservation
Tucson
Marana
Eloy
Casa Grande
Phoenix
Florence
Coolidge
Gila Bend
Willcox
Benson
San Xavier
Gila River
Indian Community
E
C
G
C
H
F
K
M
D
N
I
B
O
J
A
E
L
Figure 3.5
Initial Potential Corridors
Legend
I -10 Phoenix-Tucson Bypass Sttudy
Data Source: ALRIS 1997 - 2005, Bureau of Land Management, ADOT ATIS 2005, ADOT HPMS 2005, USGS, Bureau of Transportation Statistics
0 2.5 5 10 15 20
Miles
Scale Data Source: ALRIS 1997 - 2005, Bureau of Land Management,
ADOT ATIS 2005, ADOT HPMS 2005, USGS,
Bureau of Transportation Statistics
P:\TRANSPORTATION\ADOT_TPD\23445042_I-10_Phx_Tucson_Bypass_Study\Docs\Final Reports\Figures\Fig3.5_Initial_Corridors.pdf (ai)
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
Potential Corridor Segments
Final Report
I-10 Phoenix-Tucson Bypass Study
Arizona Department of Transportation
3-8
January 2008
URS Job No. 23445042
P:\TRANSPORTATION\ADOT_TPD\23445042_I-10_Phx_Tucson_Bypass_Study\Docs\Final Reports\Final Report\I-10 Bypass Study Final Report 01-2008.doc
Table 3-1 Initial Stakeholder Responses to Potential Corridor Alternativesa
Support Bypass
Concept
Support Potential
Corridorsb
Avoid Potential
Corridorsb
Cities
1 Benson Y H, K
2 Buckeye Y N
3 Casa Grande Y F, M, K
4 Eloy Y MKB, H-C E
5 Gila Bend Y G, K C
6 Goodyear Y G
7 Marana Y H-C
8 Maricopa Y C, F E
9 Oro Valley Y CMKB OR CFKB,
C-H
10 Safford Not Completed
11 Tucson Y H K
12 Willcox Not completed
Counties
13 SEAGO Y L K
14 Cochise Y G-M
15 Graham Y F
16 Maricopa Y C-I-K E
17 Pima Y/Nc K
18 Pinal Y ABK E,L
Other
19 Arizona State Land Dept No preferences
20 Arizona Game and Fish Dept N H(I-19 to I-10 E) C,K,L,D,B,A,J
21 Center for Biological Diversity Not completed
22 Drachman Not completed
23 Morrison Institute No preferences
24 Nature Conservancy N E K,L,C
25 Pinal Partnership Y
26 Puerto Nuevo Y/Nc H K
27 Sonoran Institute N C/O-F; H L,K,E
28 TIME Y/Nc CMK H
29 AZ Trucking Association N G
30 UPRR N for RR
a Based on interviews conducted in May and June 2007
b The corridor designations are those used in Figure 3.5.
c Y/N means partial or qualified support for bypass.
Note: Interviews with State Transportation Board Members and ADOT District Engineers not included in
tabulation.
Safford and Willcox interviews were obtained later and are shown in Table 3-3.
Final Report
I-10 Phoenix-Tucson Bypass Study
Arizona Department of Transportation
3-9
January 2008
URS Job No. 23445042
P:\TRANSPORTATION\ADOT_TPD\23445042_I-10_Phx_Tucson_Bypass_Study\Docs\Final Reports\Final Report\I-10 Bypass Study Final Report 01-2008.doc
Table 3-2 Combined Stakeholder Responses to Potential Corridor Alternativesa
Support for Bypass: 10 Cities
5 Counties (one had weak support)
1 Pinal Partnership
Limited or No Support for Bypass: AZ Trucking Association
UPRR (for rail corridor)
TIME (wants improvements to I-10)
Nature Conservancy
Sonoran Institute
Pima County
Arizona Game and Fish Department
Puerto Nuevo
Response by Corridor
Corridorb Support Avoid
A 1 1
B 3 1
C 7 3
D 1
E 1 5
F 5
G 4
H 8 1
I 1
J 1
K 8 7
L 2 4
M 5
N 1
O 1
a Based on interviews conducted in May and June 2007
b The corridor designations are those shown in Figure 3.5.
The public comments had themes similar to the stakeholders. The public input is summarized in
Chapter 9.
The corridors were also compared to the purpose and need statement presented in Section 1.5.
The stated purpose of this study is to determine if a “New” corridor is needed as a bypass for
I-10. On this basis, it was decided that all existing highways and those that are already part of an
existing plan should be treated as part of the base or “No Build” alternative. For the purposes of
analyses, these corridors are assumed to be built to the logical maximum extent as discussed in
Section 2.3. The need for a new corridor is based upon unmet needs after these routes are built or
widened and improved.
Final Report
I-10 Phoenix-Tucson Bypass Study
Arizona Department of Transportation
3-10
January 2008
URS Job No. 23445042
P:\TRANSPORTATION\ADOT_TPD\23445042_I-10_Phx_Tucson_Bypass_Study\Docs\Final Reports\Final Report\I-10 Bypass Study Final Report 01-2008.doc
Based upon this determination, initial potential Corridors E, G, N, and O were eliminated from
consideration as a new corridor but are included in the No Build alternative. Corridor H is part of
the PAG planning process but is not adopted as part of the PAG Regional Transportation Plan at
the time of this writing. Corridor H received support from stakeholders and the public, could
potentially offer some relief to I-10 in Tucson, and is significantly different that all other
alternatives. Corridor H was retained for the corridor evaluation process.
Two additional corridor ideas came from the public and stakeholder meetings. Several people
suggested a direct connection between Corridor H and Corridor C west of I-10. An eastward
extension of Corridor L near Safford and then southward along US 191 was also suggested.
These two ideas appear to have merit and were included in the set of corridor alternatives to be
evaluated.
The San Pedro Valley received the most concern from the public and stakeholders. Corridors D
and K are in that valley. Based upon very preliminary evaluation and input from the public and
stakeholders, it appears that Corridor D would be more objectionable and difficult to construct
than Corridor K. As a result, Corridor K was chosen to go into corridor evaluation. The
evaluation is presented in Section 3.4 and Chapter 4 document the extent of environmental issues
and concerns in this valley. A single alternative connection concept for Corridor K to I-10 was
chosen for further evaluation in place of Corridors A, B, and J. The concept to be evaluated
further connects to I-10 near MP 336 as suggested by several people and is a relatively straight
line that would probably not encounter significant terrain issues.
In the central portion of the corridor study (Pinal County), the number of corridor alternatives
and the general locations were modified to start the corridor evaluation process. There was
strong support from the municipalities and Pinal County for one or more east-west corridors in
the Maricopa to Coolidge area to help accommodate the expected substantial urban development
and to supplement I-8 and I-10. Corridor I was eliminated from further consideration because it
does not appear to offer relief to I-10. Corridor I may be considered by Pinal County for other
purposes.
The corridors selected to be included in the more detailed evaluation are described in the next
section.
Final Report
I-10 Phoenix-Tucson Bypass Study
Arizona Department of Transportation
3-11
January 2008
URS Job No. 23445042
P:\TRANSPORTATION\ADOT_TPD\23445042_I-10_Phx_Tucson_Bypass_Study\Docs\Final Reports\Final Report\I-10 Bypass Study Final Report 01-2008.doc
3.2 FIRST REFINEMENT OF CORRIDOR ALTERNATIVES
Based upon the review as described in Section 3.1, several corridors were selected for refinement
and are shown in Figure 3.6. This graphic was reviewed by the TAC at the June meeting and was
subsequently shown to stakeholders during interviews conducted in July 2007. Note that some of
the corridor nomenclature was modified from that shown earlier in Figure 3.5 to fit the refined
alternatives. Refer to Figure 3.6 for reference. A brief description of the alternatives is included
below:
• Corridor C – Represents the general corridor identified in the Hassayampa Regional
Framework Study. It would connect to I-10 west of SR 85 and proceed in a general
southeasterly direction, crossing SR 85 south of I-10 traversing near the northern
boundary of the Sonoran Desert National Monument passing east-west through the City
of Maricopa planning area, cross I-8 west of I-10, proceed parallel and southwest of I-10
then curve to travel eastward, cross I-10 in the Eloy planning area and proceed eastward
to connect to either Corridor F, L, or K. A variation would be to have Corridor C connect
to Corridor H and proceed west of and then south of Tucson and rejoin I-10 in the
vicinity of SR 83.
• Corridor F – Would continue the eastward direction of Corridor C in the Maricopa/Casa
Grande area and proceed eastward through the Coolidge planning area and continue
eastward crossing the San Pedro River near Mammoth and continue south of the
Aravaipa Canyon Wilderness and north of the Coronado National Forest in the Galiuro
Mountains. The corridor alternative continues eastward near Klondike and on to near
Safford where it would turn south to join US 191 south of Safford. The eastern portion of
this corridor was suggested in a public meeting.
• Corridor L – Is a variation of Corridor F that would extend southeasterly in a pass
through the upper Aravaipa Valley and the Sulpher Springs Valley to join I-10 near
Willcox.
• Corridor G – Is also a variation of Corridor F in the Casa Grande area. It would realign
I-8 starting west of I-10 and extend I-8 east of I-10 to continue as Corridor F, L, or K.
Tohono O'odham Nation
San Carlos Apache
Indian Reservation
Tucson
Marana
Eloy
Casa Grande
Phoenix
Florence
Gila Bend Coolidge
Willcox
Benson
San Xavier
Gila River
Indian Community
Safford
Maricopa
Buckeye
C
G
L
K
H
C
Figure 3.6
Corridor Alternatives - First Refinement
Legend
II--10 Phoeniix--Tucson Bypass Sttudy
0 2.5 5 10 15 20
Miles
Scale Data Source: ALRIS 1997 - 2005, Bureau of Land Management,
ADOT ATIS 2005, ADOT HPMS 2005, USGS,
Bureau of Transportation Statistics
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C
F
G
H
K
L
Refined Corridor Segments Planned Corridors
Major Rivers
City Limits
BLM
U.S. Forest Service
National Park Service
USFWS National Wildlife Refuge
American Indian Res.
Military
State Trust
Local or State Parks
Other; Private
Disclaimer:
While every effort has been made to ensure the accuracy
of this information, the Arizona Department of Transportation
makes no warranty, expressed or implied as to its accuracy
and expressly disclaims liability for the accuracy thereof.
F
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• Corridor K – Represents what appears to be the potentially most acceptable corridor in
the San Pedro Valley. It would start at either Corridor C, G, or F and extend south-eastward
in the vicinity of Mammoth or San Manual, cross the San Pedro River and then
travel southeastward east of the river and generally parallel to the river valley and then
turn eastward at the south end of the Galiuro Mountains to connect to I-10 west of
Willcox.
• Corridor H – Represents the PAG Loop Road extended northwestward to connect to
Corridor C or directly to I-10 just north of the Pinal/Pima county boundary. It would
continue southward in the Marana planning area and the Avra Valley area, cross SR 86
and continue southward near the western boundary of the Tohono O’odham Reservation
San Xavier District. It would then turn eastward and pass through the Sahuarita planning
area and join I-10 near SR 83.
These alternative corridors provide an array of options and several combinations and
permutations to be considered and evaluated. The corridors are broad study areas and do not
represent alignments.
The study team was asked to conduct additional interviews of stakeholders during the month of
July 2007. The State Transportation Board provided a list of elected officials or agency
management level people to be interviewed. A total of 14 additional interviews were conducted
involving PAG, Pima County, Marana, Pinal County, Eloy, Maricopa, Maricopa County,
Buckeye, the Southern Arizona Leadership Council, a private consultant in Tucson, and the
Tonopah Valley. The refined set of alternatives was shown to these additional stakeholder
representatives. The results are shown in Table 3-3 and are similar to results of the interviews
conducted earlier. There is, in general, strong support for the bypass idea among the cities and
counties. Corridor H is supported by Tucson area stakeholders. Corridor G and C are supported
by central Pinal County and western Maricopa County stakeholders. There was more emphasis
from the stakeholders in this round of interviews to serving existing population centers and also
recognition that finding a path through central Pinal County will be difficult due to existing and
entitled development.
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Table 3-3 Stakeholder Responses to Refined Corridor Alternativesa
Stakeholder Support Bypass
Concept
Support Potential
Corridorsb
Avoid Potential
Corridorsb
1 PAG Y No Preference
2 Pima Countyc Y H
3 Marana Y H
4 Pinal County Y G-L; G-K, C
5 Eloy Y C
6 Maricopa Y C-K
7 Maricopa County Y H-C K, L, M
8 Buckeye Not completed
9 Tonopah Valley Y C
10 Southern Arizona Leadership Council Y H
11 Private Consultant Not Completed
12 Saffordd Y F
13 Willcoxd Y K; H L; F
a Based on interviews conducted in July 2007
b The corridors are those shown in Figure 3.6 and result from the first refinement.
c Board of Supervisors passed resolution in December 2007 opposing new corridors in Pima County for I-10 Bypass.
d Positions were confirmed with city managers in December 2007.
Two people were interviewed at PAG, Pinal County, and Maricopa County for a total of 14 interviews.
Interviews with representatives of Safford and Willcox were not completed during the first round
of meetings. The city managers were contacted in December after the public meetings. Their
responses are summarized as lines 12 and 13 in Table 3-3.
3.3 CORRIDORS FOR EVALUATION – SECOND REFINEMENT
The alternative corridors presented in Section 3.2 and shown in Figure 3.6 were further refined
based on additional data incorporated into the GIS database. The corridors were completely re-labeled
with letter and number designations to provide individual segments that can be combined
and described for the evaluation. These refined alternative corridors and the new labeling system
is shown in Figure 3.7.
The GIS database was compiled from several data sources following the input provided by
agency, jurisdiction, and other stakeholder or interested party comment. The data provided by
these parties included constraints such as National Monuments, Wilderness Areas, Local and
State Parks, entitled lands, existing land cover, and protected lands. The provided data were
normalized for projection system, data format, and assigning a common valuation field.
Table 3-4 provides a list of data categories used in the analysis modeling.
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Table 3-4 GIS Data Sources
Data Category Description of Data Stakeholder
Transportation Airports Bureau of Transportation Statistics Railroads Bureau of Transportation Statistics
Arizona Protected Lands The Nature Conservancy
ACECs, National Monuments,
Wilderness Areas
Special Bureau of Land Management
Designations or
Special Interest SRP Mitigation Properties Salt River Proje

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FINAL REPORT
January 2008
I-10 Phoenix-Tucson Bypass Study
Prepared for
Transportation
Planning Division
Prepared by
in association with
Wilbur Smith Associates
I-10 Phoenix-Tucson Bypass Study
Final Report
Prepared for:
Arizona Department of Transportation
Prepared by:
URS Corporation
in Association with
Wilbur Smith Associates
January 2008
Final Report
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TABLE OF CONTENTS
EXECUTIVE SUMMARY .......................................................................................................ES-1
1.0 INTRODUCTION ...........................................................................................................1-1
1.1 ORIGIN OF THE STUDY ..................................................................................... 1-1
1.2 STUDY PROCESS................................................................................................. 1-2
1.3 PREVIOUS AND ONGOING STUDIES .............................................................. 1-3
1.4 GROWTH SCENARIOS........................................................................................ 1-3
1.5 PURPOSE AND NEED.......................................................................................... 1-6
2.0 I-10 EXISTING AND FUTURE CONDITIONS............................................................ 2-1
2.1 EXISTING CONDITIONS..................................................................................... 2-1
2.2 PLANS FOR IMPROVING I-10............................................................................ 2-3
2.3 PLANS FOR IMPROVEMENTS TO OTHER HIGHWAYS............................... 2-8
2.3.1 US 70 .......................................................................................................... 2-8
2.3.2 US 60 .......................................................................................................... 2-9
2.3.3 US 191 ........................................................................................................ 2-9
2.3.4 I-8................................................................................................................ 2-9
2.3.5 SR 85......................................................................................................... 2-10
2.3.6 South Mountain Freeway.......................................................................... 2-10
2.3.7 I-10 Reliever ............................................................................................. 2-10
2.4 OTHER MODES.................................................................................................. 2-11
2.5 2030 TRAFFIC FORECASTS ............................................................................. 2-12
2.6 NEED FOR BYPASS........................................................................................... 2-13
3.0 POTENTIAL NEW CORRIDORS.................................................................................. 3-1
3.1 INITIAL POTENTIAL CORRIDOR ALTERNATIVES ...................................... 3-1
3.2 FIRST REFINEMENT OF CORRIDOR ALTERNATIVES............................... 3-11
3.3 CORRIDORS FOR EVALUATION – SECOND REFINEMENT...................... 3-14
3.4 EVALUATION CRITERIA AND METHODOLOGY ....................................... 3-18
3.5 FINDINGS............................................................................................................ 3-28
3.6 CORRIDOR FEASIBILITY................................................................................. 3-32
4.0 ENVIRONMENTAL SCAN ...........................................................................................4-1
4.1 FATAL FLAW FACTORS .................................................................................... 4-1
4.2 OTHER ENVIRONMENTAL CONSIDERATIONS............................................ 4-1
4.3 AGENCY COORDINATION .............................................................................. 4-10
4.4 FIELD VISIT........................................................................................................ 4-11
4.5 RESULTS ............................................................................................................. 4-13
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5.0 TRAFFIC FORECASTING METHODOLOGY AND RESULTS ................................ 5-1
5.1 FORECASTING METHODOLOGY..................................................................... 5-1
5.2 FORECASTING RESULTS................................................................................... 5-4
6.0 POTENTIAL CORRIDOR FEATURES......................................................................... 6-1
6.1 CROSS SECTIONS................................................................................................ 6-1
6.2 COST ESTIMATE.................................................................................................. 6-1
7.0 FUNDING OPTIONS......................................................................................................7-1
7.1 OVERVIEW OF TRANSPORTATION FUNDING SOURCES AND
FINANCING MECHANISMS............................................................................ 7-1
7.2 ASSESSMENT OF FUNDING OPTIONS............................................................ 7-4
7.3 CONCLUSIONS AND RECOMMENDATIONS ................................................. 7-6
8.0 PUBLIC AND STAKEHOLDER INPUT....................................................................... 8-1
8.1 INTRODUCTION .................................................................................................. 8-1
8.2 PUBLIC LISTENING SESSIONS – MAY 2007................................................... 8-1
8.3 PUBLIC COMMENTS RECEIVED (PUBLIC LISTENING SESSIONS)........... 8-3
8.4 PUBLIC MEETINGS – PRELIMINARY FINDINGS
NOVEMBER/DECEMBER 2007 ....................................................................... 8-5
8.5 PUBLIC COMMENTS RECEIVED OUTSIDE OF PUBLIC MEETINGS ......... 8-8
8.6 STAKEHOLDER INTERVIEWS........................................................................ 8-11
8.7 NEWSPAPER AND MEDIA COVERAGE ........................................................ 8-14
LIST OF TABLES
Table E-1 West Segment Comparison of Route Distance and Time..................................ES-6
Table E-2 Traffic Reduction on I-10 in Tucson .................................................................ES-9
Table E-3 East Segment Comparison of Route Distance and Time .................................ES-10
Table 2-1 I-10 2005 Average Daily Traffic and Number of Through Lanes....................... 2-2
Table 2-2 Estimate of Planned Number of Lanes and 2030 Model Volumes...................... 2-6
Table 3-1 Initial Stakeholder Responses to Potential Corridor Alternativesa ...................... 3-8
Table 3-2 Combined Stakeholder Responses to Potential Corridor Alternativesa ............... 3-9
Table 3-3 Stakeholder Responses to Refined Corridor Alternativesa ................................ 3-14
Table 3-4 GIS Data Sources............................................................................................... 3-15
Table 3-5 Evaluation Criteria for Alternative Corridors .................................................... 3-18
Table 3-6 Evaluation Criteria 1 .......................................................................................... 3-19
Table 3-7 Evaluation Criteria 2 West and East Segments.................................................. 3-20
Table 3-8 Existing I-10 Speed Limits ................................................................................ 3-21
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Table 3-9 Evaluation Criteria 2 by Overall Corridor Routes ............................................. 3-23
Table 3-10 Evaluation Criteria 3 .......................................................................................... 3-24
Table 3-11 Evaluation Criteria 4 .......................................................................................... 3-25
Table 3-12 Evaluation Criteria 5 .......................................................................................... 3-26
Table 4-1 Sensitive and Federally Listed Species from AGFD.......................................... 4-2
Table 4-2 Data Suggestions from Environmental Stakeholders .......................................... 4-9
Table 4-3 Special Status Cultural Resources in General Proximity of Corridor
Alternatives ........................................................................................................ 4-10
Table 4-4 Environmental Stakeholders .............................................................................. 4-11
Table 5-1 Travel Forecast for Alternative Concepts ............................................................ 5-4
Table 6-1 Estimated Unit Costs............................................................................................ 6-3
Table 6-2 Individual Segment Cost Estimate Summary ...................................................... 6-4
Table 6-3 Proposed Route Cost Estimates ........................................................................... 6-4
LIST OF FIGURES
Figure E.1 Corridor Alternatives and Major Constraints ....................................................ES-4
Figure E.2 East Segment Comparative Routes....................................................................ES-8
Figure 1.1 Arizona’s Future Growth Pattern......................................................................... 1-5
Figure 2.1 2004 Traffic Volumes and Truck Percentage ...................................................... 2-3
Figure 2.2 MAG I-10 Improvements .................................................................................... 2-8
Figure 3.1 Environmental Constraints................................................................................... 3-2
Figure 3.2 Land Ownership................................................................................................... 3-3
Figure 3.3 Topography.......................................................................................................... 3-4
Figure 3.4 Existing Transportation System........................................................................... 3-5
Figure 3.5 Initial Potential Corridors .................................................................................... 3-7
Figure 3.6 Corridor Alternatives – First Refinement .......................................................... 3-12
Figure 3.7 Corridors for Evaluation – Second Refinement................................................. 3-16
Figure 3.8 Alternative Corridor Segments Used in Evaluation........................................... 3-17
Figure 4.1 Grasslands and Riparian Forests........................................................................ 4-14
Figure 4.2 Wildlife Connectivity......................................................................................... 4-16
Figure 4.3 Priority Conservation Areas............................................................................... 4-18
Figure 6.1 Proposed Cross Sections ...................................................................................... 6-2
LIST OF APPENDICES
A Prior and Ongoing Studies
B Technical Memorandum, Travel Demand Forecasting
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EXECUTIVE SUMMARY
The I-10 Phoenix-Tucson Bypass Study was conceived to address existing and future traffic
congestion in the two major metropolitan areas of Arizona. Arizona has been one of the fastest
growing states in the nation for the past four decades, and most people believe this trend will
continue. Traffic has increased even faster than the phenomenal population growth.
The purpose of the bypass study is to make a preliminary assessment of the need for and
feasibility of a new transportation corridor that would provide an alternative to I-10 to divert
through traffic out of the congested metropolitan areas.
1.0 OVERVIEW
1.1 Study Process
The study began in April 2007 and was designed to be completed by the end of 2007. A
Technical Advisory Committee (TAC) was formed consisting of representatives from Arizona
Department of Transportation (ADOT), Federal Highway Administration (FHWA), Maricopa
Association of Governments (MAG), Central Arizona Association of Governments (CAAG), and
Pima Association of Governments (PAG). The committee met several times during the course of
the study to provide review and guidance to the study team.
Initial public meetings were held in May 2007 in Benson, Tucson, Eloy, and Buckeye. These
meetings were very well attended, and many verbal and written comments were received
regarding the purpose and need of the bypass, issues and concerns, and the initial array of
potential alternative corridors. A second round of public meetings was held in November and
December. Locations included Benson, Tucson, Casa Grande, Buckeye, Marana, Safford, and
Willcox. The preliminary findings from the study were presented for review and comment.
Verbal comments were summarized on flip charts, comment forms were received and tabulated
and electronic comments were recorded. Presentations were made to PAG and MAG.
ADOT, the State Transportation Board, and the TAC provided a list of stakeholders to be
interviewed. A total of 42 interviews were conducted in May-July 2007. These interviews
provided insight into initial opinions and preferences of the stakeholders and provided
information used to refine the corridor initial alternatives.
A field tour was conducted on September 6 and 7 and hosted by The Nature Conservancy.
Several other agencies with interests in the San Pedro River Valley also participated. The tour
provided information about specific areas of concern in the San Pedro and Aravaipa valleys and
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enabled the study team to visually inspect some of the more critical areas being considered for
the corridor alternatives.
Preliminary findings were presented to the State Transportation Board at a study session on
November 5, 2007. Refined study findings were presented following the second round of public
meetings at a regular Board meeting on December 21, 2007.
1.2 Corridor Alternatives Development
The initial idea for this bypass study came from the State Transportation Board. Based on
discussions at a Board meeting in December 2006, a corridor concept appeared in a newspaper
article. The concept showed a corridor extending from I-10 west of Buckeye to I-10 near Casa
Grande and continuing to I-10 near Willcox. This concept illustrated the fundamental idea that
the State Transportation Board wanted ADOT to study.
The study team took this basic concept and developed a broad array of initial potential corridors.
Refer to Figure 3.5 in Chapter 3. This array of corridors was presented at the initial public
meetings in May to provide a basis for discussion of the fundamental concept and to identify
variations to this initial array of alternatives. Initial graphics showing environmental constraints,
land ownership, topography, and the existing transportation system were also shown to the
public. Through the study process, these graphics were refined and are shown in Figures 3.1
through 3.4.
A Purpose and Need Statement was developed and presented to the public and stakeholders.
Minor refinements were made, and the final statement is presented as follows:
Purpose
• To provide an additional high-capacity transportation corridor to accommodate travel across
southern and central Arizona.
Need
• Provide alternative route to I-10 to relieve traffic congestion on I-10 in the Phoenix and
Tucson metropolitan areas.
• Provide a shorter, faster route through southern and central Arizona that will attract through
trucks and other traffic from I-10.
• Provide a new route that offers an alternative path for I-10 traffic during construction,
maintenance, and incidents.
• Provide a new transportation corridor to serve the expected rapid population growth and land
development in the Sun Corridor.*
• Develop a corridor that is context sensitive to environmental and social elements.
* The Sun Corridor is one of a dozen future mega-metropolitan areas identified in the United States and could stretch
from Prescott to Sierra Vista.
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The following is a brief description of the material covered in each chapter of the final report.
The findings are summarized in Sections 2 through 5 of this Executive Summary.
The need for the bypass corridor was examined by comparing the number of existing lanes on
I-10 to the existing traffic volumes. Plans for future widening of I-10 and other related routes
were also identified. The ability to widen I-10 through Tucson is very limited and provides a
major reason for considering a bypass. These data are presented in Chapter 2.
The initial potential corridors were refined based upon additional information regarding
constraints, input from stakeholders, and the field tour. The final set of alternatives used in the
evaluation is shown in Figure E.1. The major constraint areas including environmental
constraints, Indian reservations, and existing and entitled urban development are also highlighted
in this graphic.
The refined alternatives were evaluated based on criteria derived from the Purpose and Need
Statement. The evaluation is included in Chapter 3.
An environmental scan was prepared to identify the major constraints to the corridors and to
identify environmental issues associated with those corridors. The constraints are shown in detail
in Figure 3.1, and the scan is described in Chapter 4.
Given the very preliminary nature of this study, computerized traffic modeling to forecast traffic
was not prepared. Instead, a manual method was developed, documented in a Technical
Memorandum included in the Appendix and summarized in Chapter 5. These forecasts only
address long trips and through-Arizona traffic. Localized traffic from urban development along
the corridors is not included. This local urban travel demand is being addressed in other state,
regional, or local studies. The forecasts developed for this study are believed to provide a
reasonable basis for determining the amount of traffic that might be diverted from I-10 and the
volume of long-trip and through traffic that might use the potential corridor. The forecasts were
helpful in determining need and feasibility.
The basic roadway cross-section needed for the corridor was identified based on the long-trip
needs. Urban traffic on the corridors may require additional lanes. A very preliminary, order of
magnitude cost estimate was made for the corridor alternatives. This information is discussed in
Chapter 6.
Potential sources of funding were identified for the corridor and discussed in Chapter 7.
The public meetings and stakeholder involvement are documented in Chapter 8.
Sonoran Desert
National Monument
Ironwood Forest
National Monument
San Pedro Valley
Saguaro National
ParkTucson
Mountain District
Santa
Catalina
Mountains
Santa Teresa
Wilderness
Aravaipa
Canyon
Wilderness
Galiuro
Mountains
Rincon
Mountains
Eagletail
Mountains
Wilderness Tonopah
Valley
Goodyear
Sierra Estrella
Wilderness
Organ Pipe
National Monument
and Wilderness
Aravaipa Valley
Coronado
National
Forest
Coronado
National
Forest
Coronado
National
Forest
Pinaleno
Mountains
Willcox
Playa
Sulphur
Springs
Valley
Allen
Flat
Proposed
Park
Avra
Valley
Proposed
Park
South Mountain
Park
Haley Hills
San Carlos Apache Indian Reservation
Tucson
Marana
Eloy
Casa Grande
Phoenix
Florence
Gila Bend Coolidge
Willcox
Benson
San Xavier
Gila River
Indian Community
Safford
Maricopa
Buckeye
PIMA
PINAL
MARICOPA
GRAHAM
GILA
COCHISE
GREENLEE
APACHE
NAVAJO
C1
C2
D1
D2 E1
E2
F1
F2
F3
G
H
I
K1
K2
L
M1
M2
Legend
0 2.5 5 10 15 20
Miles
Scale Data Source: ALRIS 1997 - 2005, Bureau of Land Management,
ADOT ATIS 2005, ADOT HPMS 2005, USGS,
Bureau of Transportation Statistics
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Figure E.1
Corridor Alternatives
and Major Constraints
II--10 Phoeniix--Tucson Bypass Sttudy
Major Constraints
Major Rivers
State Routes
Existing Urban Land
Entitled Land
Indian Reservation
Environmental Limitations to Corridor
Disclaimer:
While every effort has been made to ensure the accuracy
of this information, the Arizona Department of Transportation
makes no warranty, expressed or implied as to its accuracy
and expressly disclaims liability for the accuracy thereof.
Corridor locations are conceptual. Alignments would be determined
following the completion of appropriate design and environmental
studies.
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2.0 FINDINGS
The determination of need for the project is based on the Purpose and Need Statement. The
following summarizes the findings of this study regarding the need. The discussion is separated
into two segments: West Segment (Buckeye to Casa Grande) and East Segment (Casa Grande to
Willcox).
2.1 West Segment
The SR 85/I-8 route is designated as the Phoenix I-10 Bypass. I-8 is a four-lane interstate
highway that is currently underutilized. SR 85 is being upgraded to a four-lane divided limited
access highway. When the improvements to SR 85 are completed, a free-flow bypass will exist
for through traffic to avoid the Phoenix area. This bypass will probably have the capacity to
accommodate the bypass traffic demand for many years.
When extensive urban development occurs in the Tonopah Valley-Buckeye-Goodyear-Maricopa
area, additional freeways may be needed to serve the urban traffic. Corridor C was derived from
the MAG Hassayampa Valley Roadway Framework Study. The corridor is planned to be a part
of the expanding urban freeway system and would link into other components of that system.
The need for the roadway is largely dependent upon the timing and rate of development in that
part of Maricopa and Pinal counties.
Selection of Route: Only one new corridor alternative was identified for the west segment due to
major constraints created by the Sonoran Desert National Monument, the Estrella Mountains, the
Gila River, two Indian reservations, and entitled lands in Goodyear and Maricopa. Corridor C
could connect to I-10 north of Casa Grande (Corridor C2) or connect to I-8 (Corridor D1). Refer
to Figure E.1.
Relieve Traffic Congestion in Phoenix: The projected traffic volumes by MAG in Phoenix
indicate that all planned freeways will be operating at full capacity in 2030. The traffic forecasts
prepared for this study indicate that the west segment could relieve I-10 by 44,100 vehicles per
day (vpd) in 2030 and 97,100 vpd in 2050. The increase in diversion between 2030 and 2050
reflects the acceleration of growth in western Maricopa County and the worsening traffic
congestion in Phoenix. The traffic to and from western Maricopa County that wants to go to
Casa Grande, Tucson or points east, would use the potential bypass and avoid going through the
rest of the Phoenix area. The traffic reduction equates to one lane in each direction in 2030 and
two lanes in each direction in 2050.
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Provide a Shorter, Faster Route: Table E-1 provides a comparison of the distance and time on
I-10, SR 85/I-8 and Corridor C. Corridor C is approximately 10 miles shorter than existing I-10
and 15 miles shorter than the current SR 85/I-8 bypass. It would reduce travel time compared to
existing I-10 by 14 minutes in off-peak and 31 minutes in peak times based upon projected 2030
conditions. In comparison with the SR 85/I-8 existing bypass, Corridor C would provide travel
time savings of approximately 8 minutes in the off peak and 10 minutes in the peak.
Table E-1
West Segment Comparison of Route Distance and Time
Travel Time (minutes) Time Savings (minutes)b
Routea
Lengths
(miles) Off Peak Peak Off Peak Peak
I-10 100 92 128 – –
SR 85 / I-8 105 86 97 6 31
C1-D1 90 78 87 14 41
a I-10 MP 98 west of Buckeye to I-10/I-8 interchange in Casa Grande
b As compared to I-10 in 2030
If Corridor C is constructed at some future date to serve the expanding urban area, it will likely
replace the function of SR 85/I-8 as the I-10 Bypass because it will be a shorter, faster route.
Provide an Alternative Route to I-10: The potential new corridor would provide an additional
alternative route to I-10; however, SR 85/I-8 already provides an alternative from Buckeye to
Casa Grande. Some planned additional freeways in Phoenix will also provide alternative routes
within the urban area.
Serve the Expected Growth in the Sun Corridor: Population forecasts provided by MAG from
the Hidden Valley Roadway Framework Study indicate the population of the portion of Maricopa
and Pinal counties that would be generally served by a potential corridor such as Corridor C
could range from 400,000 to 700,000 in 2030 and into the millions in later years. When growth
of this magnitude occurs, a new corridor such as Corridor C would be needed.
Develop a Corridor that Is Context Sensitive to Environmental and Social Elements: If the
corridor is planned and preserved, it can fit well within the future urban fabric planned for the
area. There is a wildlife corridor extending between the Sonoran Desert National Monument and
the Sierra Estrella Wilderness. Provisions for maintaining this corridor would need to be
incorporated into the design of a roadway corridor.
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2.2 East Segment
The East Segment would extend from I-10 in Casa Grande to I-10 near Willcox. Of the several
alternative corridors shown in Figure E.1, Corridor F1 would connect to I-10 north of Casa
Grande while Corridor G would be more or less a direct eastward extension of I-8 and
Corridor E1 would connect with I-10 in Eloy. If F1 were chosen as the corridor, then
Corridors C1 and C2 would also have to be chosen and constructed to provide a continuous
bypass.
To simplify the comparative summary of findings, it was decided to use alternative Corridors G
and E1 to form the alternatives. These corridors connect into I-10 at a location that would enable
traffic to continue to use SR 85/I-8 as the West Segment I-10 Bypass or they could connect into
either Corridor C2 or D1 if a new I-10 Bypass route were chosen and constructed for the West
Segment. On this basis, alternative routes comprised of various corridor sections were chosen to
illustrate the findings of this preliminary assessment of the East Segment.
Selection of Routes for Comparison: The numerous potential corridor alternatives that were
developed and studied are shown in Figure E.1. From these several possibilities, four corridors
were chosen that connect to I-8 and appear to be logical potential corridors that would meet the
purpose and need for the east segment of the bypass. These four corridors are labeled as
“Routes” and are shown in Figure E.2. All of these routes connect into the I-10/I-8 interchange
either as a new leg of that interchange or via existing I-10. Other corridors and sections identified
in Chapter 3 were not eliminated but simply were not used in this summary analysis to determine
whether or not there are corridors that could meet the purpose and need of the bypass.
The M2 section that would extend to Safford and utilize US 191 to I-10 was not included
because it is a longer route than existing I-10. The D1 section was modified to connect into the
I-10/I-8 interchange as the south leg. This revision is compatible with concepts being studied as
part of the Southern Pinal/Northern Pima Corridor Definition Study. The E1 section could be
extended to the west to connect with the D1 section. It was stopped at I-10 in Eloy just to provide
more variation in the comparative summary evaluation.
Relieve Traffic Congestion in Tucson: Traffic volumes on I-10 through Tucson in 2005 exceed
150,000 vpd. Forecasts by PAG indicate that traffic demand on I-10 in 2030 could exceed
300,000 vpd. ADOT is constructing or has plans to build four lanes in each direction through
Tucson. That is the maximum number of lanes that can fit within the very confined right-of-way.
Since the estimated capacity of an eight-lane freeway is 196,000 vpd, some relief to the future
traffic is needed.
Sonoran Desert
National Monument
Ironwood Forest
National Monument
Buenos Aires
National Wildlife
Re fuge
Mt. Wrightson
Wilderness
Las Cienegas
NCA
San Pedro Valley
Saguaro National
ParkTucson
Mountain District
Santa
Catalina
Mountains
Santa Teresa
Wilderness
Aravaipa
Canyon
Wilderness
Galiuro
Mountains
Rincon
Mountains
Aravaipa Valley
Coronado
National
Forest
Coronado
National
Forest
Coronado
National
Forest
Pinaleno
Mountains
Willcox
Playa
Sulphur
Springs
Valley
Allen
Flat
Proposed
Park
Avra
Valley
Proposed
Park
Haley Hills
Tohono O'odham Nation Tucson
Marana
Eloy
Casa Grande
Florence
Coolidge
Willcox
Benson
San Xavier
Safford
Maricopa
Route 1
Route 2
Route 3
Route 4
PIMA
PINAL
COCHISE
GRAHAM
MARICOPA
SANTA CRUZ
GILA GREENLEE
D1
E1
F2
G
H
I
K1
K2
L
M1
Legend
0 2.5 5 10 15 20
Miles
Scale Data Source: ALRIS 1997 - 2005, Bureau of Land Management,
ADOT ATIS 2005, ADOT HPMS 2005, USGS,
Bureau of Transportation Statistics
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Figure E.2
East Segment Comparative Routes
II--10 Phoeniix--Tucson Bypass Sttudy
Major Rivers
State Routes
Disclaimer:
While every effort has been made to ensure the accuracy
of this information, the Arizona Department of Transportation
makes no warranty, expressed or implied as to its accuracy
and expressly disclaims liability for the accuracy thereof.
Corridor locations are conceptual. Alignments would be determined
following the completion of appropriate design and environmental
studies.
Major Constraints
Existing Urban Land
Entitled Land
Indian Reservation
Environmental Limitations to Corridor
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The potential traffic reduction in Tucson in 2030 and 2050 is shown in Table E-2. Routes 1, 2,
or 3 would reduce traffic on I-10 by 14,500 vpd in 2030 and 20,000 vpd in 2050. This volume
equates to approximately 0.3 lanes in each direction in 2030 and 0.4 lanes in each direction in
2050. The reduction in traffic amounts to 7% to 10% of the planned roadway capacity
(196,000 vpd). This reduction would help relieve congestion in Tucson by a modest amount.
Table E-2
Traffic Reduction on I-10 in Tucson
2030 AADTa
Percent of
Capacityb 2050 AADTa
Percent of
Capacityb
Route 1, 2, or 3 14,500 7% 20,000 10%
Route 4 32,700 17% 72,800 37%
a Average annual daily traffic total two-way.
b Capacity of eight lanes = 196,000. See Travel Demand Forecasting Technical Memorandum, October 4, 2007, by
Wilber Smith Associates, p. 19 for derivation of capacity.
With Route 4, the reductions would be greater than with Routes 1, 2, and 3. The amounts equate
to 17% and 37% of the planned capacity. The reduction in 2050 equates to 1.5 lanes in each
direction. Some of this reduction to I-10 traffic would come from the diversion of I-19 traffic
going to/from Mexico but not destined for Tucson. This I-10 through traffic would join I-10 east
of Tucson if headed for New Mexico or northwest of Tucson if headed for Phoenix or California.
If both Route 4 and either of the Routes 1, 2, or 3 are built, the greatest reduction in traffic in
Tucson would be realized. The amounts equate to 20% in 2030 and 42% in 2050 of the planned
roadway capacity and would make a significant difference in the excess demand and traffic
congestion on I-10 in Tucson.
Provide a Shorter, Faster Route: Table E-3 provides comparative data on distances and travel
time for I-10 (in 2030) and for the four route alternatives used in this summary evaluation.
Routes 1, 2, and 3 would provide a shorter and quicker route than existing I-10. Distance savings
range from 6 to 15 miles and the time savings would be approximately 13 to 17 minutes in the
off-peak hours and 33 to 36 minutes in the peak hours. The shorter, faster routes will attract
through traffic from I-10, including many large trucks that have no destination in the Tucson
area. The distance and time savings can help to reduce the cost of goods and services as well as
benefiting all motorists on the new bypass and those that remain on I-10 because of the reduced
congestion.
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Table E-3
East Segment Comparison of Route Distance and Time
Travel Time (minutes) Time Savings (minutes)b
Routea
Lengths
(miles) Off Peak Peak Off Peak Peak
I-10 150 132 167 – –
Route 1 135 116 131 16 36
Route 2 144 119 134 13 33
Route 3 138 115 131 17 36
Route 4 178 153 170 (21) (3)
a I -10/I -8 interchange in Casa Grande to I -10 MP 348 east of Willcox
b As compared to I-10 in 2030
Route 4 would be longer and would not reduce travel time for I-10 through traffic; however, by
reducing congestion on I-10, it would provide benefits to motorists on I-10.
Provide an Alternative Route to I-10: Currently there are no alternative routes to I-10 through
southern Arizona. Traffic incidents or construction can create untenable situations on this
essential lifeline for Tucson and Phoenix and much of the Southwest. The potential bypass routes
would provide an alternative route to I-10. With appropriate traveler information systems,
motorists could choose the alternative route if there are unfavorable conditions on I-10 even if
they might have otherwise chosen to stay on I-10. Routes 1, 2, and 3 require motorists to make
the route decision near Casa Grande for eastbound travelers and near Willcox for westbound
travelers. As a result, the alternative route would only apply to long distance and through trips.
Route 4, because it is longer than I-10, would not attract I-10 through trips except when traffic
conditions in Tucson are at their worst. However, because Route 4 roughly parallels I-10 from
Casa Grande to Tucson, it would provide numerous opportunities for motorists to divert from
one route to the other depending on traffic conditions and advance information provided by
traveler information systems. I-10 between Casa Grande and Tucson is expected to be more
heavily traveled than I-10 east of Tucson. Route 4 may provide a more valuable alternative
corridor than Route 1, 2, or 3.
Serve the Expected Growth in the Sun Corridor: Population in Arizona is projected to
increase from 6.2 million in 2006 to 10.3 million in 2030. Population forecasts for 2050 range
from 12.8 million to 16 million. The five-county study area (Maricopa, Pinal, Pima, Cochise, and
Graham) includes about 83% of the current population of the state and is projected to contain
85% in the future. Pinal County is expected to be the fastest growing on a percentage basis and
could have an urban area comprised of the cities of Maricopa, Casa Grande, Coolidge, Eloy, and
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Florence that could exceed the population of the current Tucson Metropolitan Area. Preservation
of corridors through this area is very important to the long-term vitality of this growing area.
Most of the growth is currently expected to occur west of SR 79 in Pinal County. Routes 1, 2,
and 3 would provide an east-west corridor that could be part of the major highway plan for the
area. Route 4 would pass through more of the area expected to develop and thus may serve a
greater need in Pinal County.
Routes 1, 2, and 3 could also serve areas that currently are not expected to be highly urbanized.
Communities that could receive significant economic stimulus from the bypass include all of
eastern Pinal County including the communities of Dudleyville, San Manual, and Mammoth. In
addition, Cochise County and Willcox could receive economic stimulus. If a connection is made
to Safford (Corridor M2 in Figure E.1), a linkage would be provided between central Pinal
County and the largest urban center in Graham County thus connecting two areas that are
expected to grow significantly over the next few decades.
Develop a Corridor that Is Context Sensitive to Environmental and Social Elements: The
eastern end of Routes 1, 2, and 3 is comprised of Sections F3, M1, L, K1, and K2. All of these
sections are near areas that have numerous environmentally sensitive properties. The corridors
have been identified to avoid encroaching on any of the protected lands, but the corridors are in
general proximity to several national forests, wilderness areas, areas of critical environmental
concern, and areas set aside for preservation of wetlands and riparian habitat. Some stakeholder
agencies have expressed great concern regarding the potential impact that a new highway would
have primarily due to the potential inducement of urban development that could compete for the
groundwater supply in the river watersheds that makes the area unique and valuable as a natural
preserve. The concern is primarily directed at the San Pedro Valley and to a somewhat lesser
extent the Aravaipa Valley.
The routes through these areas would need to accommodate wildlife crossings, preservation of
native vegetation, and incorporate design features that enhance the area and make the roadway
compatible with its surroundings.
Minimizing the potential of urban development in the most sensitive areas would need to be
addressed. Selection of interchange locations would be the most critical element. Since the
corridors mostly pass through State Trust Lands, extensive coordination with the Arizona State
Land Department would be needed.
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Section M1 of Route 1 would pass through approximately 14 miles of rugged mountainous
terrain. Currently, this area is only accessible by four-wheel-drive vehicles. In the middle of the
section, those jeep trails are difficult to use by any vehicle. Design of a roadway through this
area will require exceptional effort to minimize impacts and develop a pleasing roadway that
does not create an unrepairable scar on the landscape. If properly designed, the roadway would
provide a very scenic drive for motorists.
Route 4 would avoid the sensitive areas that have received the most discussion from stake-holders;
however, it is not without controversy. The Avra Valley west of the Tucson Mountains
is an environmentally sensitive area that lies between the Ironwood National Monument and the
Saguaro National Park Tucson Mountain District. Several people at public meetings expressed
concern about a new roadway corridor in that general area.
The Tucson Mitigation Corridor (approximately 4.25 square miles) was established as mitigation
for construction of the Central Arizona Project Canal. This area lies along Sandario Road south
and west of Tucson Mountain Park. The Tohono O’odham Indian Reservation is on the west side
of Sandario Road. For a two-mile long stretch, the right-of-way for Sandario Road provides the
only space between the Indian Reservation and the Mitigation Corridor. For this roadway
corridor to be viable, the ability to work out some land exchange with the Mitigation Corridor
would be needed.
3.0 FEASIBILITY
The several corridor alternatives were evaluated to determine feasibility based on avoidance of
protected environmental areas, engineering challenges, benefit/cost, and public/stakeholder
acceptance. Based on the preliminary assessment made as part of this study, there are several
corridors that appear to be feasible.
All of the corridors shown in Figure E.1 avoid direct encroachment of all protected lands and
Indian reservations with the exception of a two-mile stretch of Corridor H as discussed above.
With this one potential exception, no other fatal flaws were found.
All of the corridors appear to offer routes that can be engineered and constructed. The most
difficult section is M1. A very preliminary route location was developed that appears to be
feasible. The cost per mile would probably exceed most other rural sections but would be
somewhat comparable in complexity to SR 87 through the area near the Maricopa/Gila County
line. Several major bridges with tall piers may be needed in this section, but it appears that none
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of them would be long-span structures. It appears that grades can be kept to 6% or less with
some cuts and fills reaching 200 feet in height.
The second-most-challenging section is K1 in the San Pedro Valley. It would pass through
rolling terrain with numerous washes on the western slope of the Galiuro Mountains. Based on a
very preliminary examination of topographic mapping, no major engineering issues were noted.
Routes 1, 2, and 3 are projected to carry 17,000 vpd in 2030 and 24,000 vpd in 2050. These
forecasts are based on growth of long-trip and through traffic and do not include traffic that
might be generated by urban growth along the corridor. By comparison, today I-10 east of
Benson carries approximately 15,000 vpd with 30% to 45% heavy trucks. I-8 carries less than
10,000 vpd today. Data supplied by FHWA indicate that in 2005, of the national rural interstate
system (30,000 miles), 22% carried fewer than 10,000 vpd and 52% carried fewer than
20,000 vpd. The projected traffic volumes on the alternative corridors for the I-10 Bypass fall
well within the range expected on rural interstates. A formal benefit cost analyses has not been
conducted.
There is considerable stakeholder opposition to Routes 1, 2, and 3 due to the proximity to
environmentally sensitive areas and concern that a new highway would attract urban
development. The areas are unique due to the riparian habitats along the San Pedro River and
Aravaipa Creek. Urban development would probably draw groundwater that is a critical part of
the watersheds of these two flowing streams and, therefore, could jeopardize years of effort to
protect the water sources for restoration and conservation of these rivers.
Routes 1, 2, and 3 pass through areas that are surrounded by mountain ranges that are in the
Coronado National Forest. The valleys are generally undeveloped and are mostly State Trust
Lands. As a result, a vast sparsely populated area is created that provides habitat for many large
mammals, numerous bird and fish species (some federally protected species), and some unique
native grasslands. Some stakeholders wish to retain this area as a large undeveloped “preserve”
and have the opinion that all growth should take place in the existing major urban areas.
On the other hand, much of the developable land is State Trust Land which is to provide the
maximum financial return to benefit the public education system. Should, or can, all of this land
be protected and left undeveloped? There may be long-term benefits to Arizona of providing
economic stimulus to existing small communities near the corridors and even development of
new small communities. The new communities could give people an opportunity to live near
major preserved areas such as the national forests.
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Decisions about where growth should take place are well beyond what can be addressed in this
study. Since currently there are no adopted land use plans that include urban development in
eastern Pinal County or in the more sensitive areas of Routes 1, 2, and 3, it is reasonable to
assume that urban development in those areas is not desired. Such plans can change in the future.
If a new highway corridor were to be proposed, local jurisdictions and counties may view future
land use in the corridor areas in a different light.
4.0 ROADWAY CROSS-SECTION AND COST ESTIMATES
For the bypass to divert significant traffic from I-10, it needs to provide free-flow conditions that
make the route faster than staying on I-10. Truck traffic would likely be a major component of
the bypass traffic. Given the Arizona terrain, grades (inclines) will be encountered so that trucks
will not always be able to maintain speeds of smaller vehicles. As a result, a four-lane divided
highway appears to be the minimum acceptable roadway. A two-lane highway may be con-sidered
to establish the corridor, but a four-lane roadway will be needed to divert much traffic.
A standard ADOT cross-section with a minimum right-of-way of 308 feet is recommended.
Additional right-of-way will be needed for interchanges, cut and fill slopes, and some drainage
features.
The order of magnitude cost estimates for the entire 250 mile corridor alternatives range between
$6 and $8 billion. The east segment (150+ miles) would cost $2 to $3 billion. The lower cost per
mile for the East Segment compared to the West Segment is due to rural conditions instead of
urban which results in fewer interchanges per mile, less expensive interchanges, and two lanes
each direction instead of three.
5.0 FUNDING
The bypass cannot be constructed with current funding levels. The federal and state fuel tax rates
have not been increased for almost 15 years, and the receipts have been increasing at a slower
rate than traffic increases due to more fuel-efficient vehicles and some alternative fuel usage.
Construction cost increases have far outstripped any highway user fund increases. As a result,
recent projections indicate that the Federal Highway Trust Fund could be approximately
$4 billion in the red by 2009. It would take a 10-cent increase in both the federal fuel tax
(assuming Arizona continues to get its current percentage) and the Arizona fuel tax and to devote
the entire amount of both increases to construct the complete bypass.
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The bypass might be built as a toll road. Very preliminary estimates indicate that it may be
difficult to fund the full amount through tolls because traffic volumes are sensitive to tolling
rates. The trucking association has indicated opposition to toll roads.
6.0 PUBLIC AND STAKEHOLDER OPINIONS
Based upon the stakeholder interviews conducted during the study, all twelve cities contacted
expressed general support for the concept of a new highway corridor. Some cities preferred
certain corridors and opposed others. Of the five counties contacted, three expressed support for
the concept of a new highway corridor while Pima County passed a resolution in December
opposing any new corridor for the I-10 Bypass in the county. Cochise County Board of
Supervisors is opposed to the bypass corridor in the San Pedro Valley.
The Arizona Trucking Association did not support the concept due to concern about funding and
value. Similarly, the T.I.M.E. organization expressed concern that discussions of the I-10 Bypass
might detract from the efforts to fund and construct improvements to I-10. The Union Pacific
Railroad expressed no interest in investing in a new rail corridor since they are investing heavily
in double tracking the existing corridor.
The Arizona Game and Fish Department, the Nature Conservancy, the Cascabel Working Group,
the Defenders of Wildlife and several other environmental-oriented groups expressed significant
opposition to a new corridor particularly in environmentally sensitive areas including the
Araviapa Valley, the San Pedro Valley and the Avra Valley.
The public meetings were all very well attended and scores of comments were received and
recorded. Major themes from these comments are summarized in Chapter 8. Many people were
opposed to some or all of the corridor options due to concern about adverse impact on the
environment and wildlife, impact to rural lifestyles and agricultural lands, and cost. Some people
questioned the population and traffic forecasts based upon limitations on water and petroleum
supplies. Others opined that the corridors east of Tucson would not divert sufficient traffic from
I-10 in Tucson to justify the cost of the bypass or its potential adverse affect on the environment.
Other attendees at the public meetings expressed support for the concept and cited the need to
accommodate continued increases in traffic (particularly trucks) and to preserve corridors
through the rapidly developing areas. Many people believe that major improvements are needed
to the state’s transportation system of highways and railroads.
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7.0 CONCLUSIONS
a. Stakeholders and the public emphasized the most pressing need is to widen and improve I-10
to the maximum extend reasonable, complete the SR 85/I-8 bypass, build the planned
freeway system in the greater Phoenix Metropolitan Area, widen and improve US 60/US 70
from Apache Junction to Safford.
b. The expected continued rapid growth in Arizona will place a huge burden on the state’s
highway system. The emerging Sun Corridor is projected to be home to 10 million or more
residents over the next few decades. Identification and preservation of future transportation
corridors to serve this mega-metropolitan area is essential to the livability of the area and its
economic vitality.
c. Based upon this preliminary assessment, there appears to be a need for an I-10 bypass.
Several alternative corridors have been identified that would offer some relief to traffic
congestion in the Phoenix and Tucson metropolitan areas, would provide a shorter and faster
route, would provide an alternative route to I-10, and would serve the rapidly developing Sun
Corridor.
d. All potential I-10 bypass corridors must pass through central Pinal County where substantial
growth is taking place. Large blocks of land have already been approved for development or
“entitled.” Preservation of a corridor through this area should be of very high importance.
e. All identified alternative corridors appear to be technically feasible and can be located so that
none would encroach on any currently preserved lands (with the possible exception of
Corridor H). Those corridors that would pass through the San Pedro Valley or the Aravaipa
Valley are opposed by very organized and vocal groups that want these valleys to remain
largely undeveloped to preserve the ground water sources for these streams and the wildlife
habitat. There is opposition to the I-10 Bypass in Avra Valley by the Pima County Board of
Supervisors and some residents of the area.
f. Due to the proximity of the potential corridors to large preserved lands, roadways would
need to be designed using context sensitive elements to accommodate wildlife crossings
where needed and to incorporate aesthetic treatments that help to blend the roadways into the
existing environment.
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g. Much of the potential corridors would be on State Trust Land. Early coordination with the
State Land Department will be needed.
h. Major expansions of existing transportation funding sources and new funding sources are
needed to meet the needs in Arizona and particularly to construct a new 250-mile highway.
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1.0 INTRODUCTION
The I-10 Phoenix-Tucson Bypass Study was requested by the Arizona State Transportation
Board. The purpose of the study is to make a “Preliminary assessment of the need and feasibility
for a new transportation corridor that would provide an alternative to I-10.” In particular, the
study is to determine if there is a need for a new major highway corridor through the state that
would provide an alternative route to Interstate 10 (I-10) through the Phoenix and Tucson
metropolitan areas and determine if there are one or more potentially feasible corridors for such a
route.
1.1 ORIGIN OF THE STUDY
Members of the State Transportation Board recognized that I-10 through the Tucson area is
getting more congested every day and that severely limited right-of-way limits the widening of
I-10 to four lanes in each direction. With recent forecasts by the Pima Association of
Governments (PAG) of over 200,000 vehicles per day (vpd), I-10 will become very overloaded.
In December 2006, the idea of an I-10 bypass was first discussed informally by the State
Transportation Board. A newspaper article appeared in the Arizona Daily Star that reported on
this meeting and suggested a bypass route that would depart from I-10 between Willcox and
Benson, cross I-10 in the vicinity of Casa Grande, and rejoin I-10 west of State Route (SR) 85.
Such a corridor could offer a shorter, faster route that would divert through traffic, including
truck traffic, out of Tucson and Phoenix and thereby offer some congestion relief in these
metropolitan areas.
On January 16, 2007 C.H. Huckelberry, Pima County Administrator, sent a letter to Si Shorr,
Vice Chairman of the State Transportation Board, supporting the idea of such a bypass and
identifying some of the expected benefits. He also suggested that the corridor be multimodal
including railroad and utility corridors. Similarly, on January 18, 2007, Richard Myers,
Chairman of the Southern Arizona Leadership Council, sent a letter to Joe Lane, Chairman of the
State Transportation Board, supporting the need for a study of such a bypass.
On January 18, 2007, the State Transportation Board requested that the Arizona Department of
Transportation (ADOT) Transportation Planning Division (TPD) undertake a study of the I-10
Phoenix-Tucson Bypass. URS Corporation (URS) was selected to conduct this study and
received a task order dated March 27, 2007.
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1.2 STUDY PROCESS
The study process generally followed the scope of services included in the Request for Proposal
and further defined in the URS proposal dated February 27, 2007. The State Transportation
Board requested that the study be completed as rapidly as possible. A six-month schedule was
proposed. Ten tasks were identified as follows:
1. Identify and describe all relevant studies that have been completed are ongoing.
2. Identify the potential general corridor or corridors.
3. Estimate travel demand.
4. Identify the number of lanes and road cross section.
5. Estimate the cost.
6. Identify potential fatal flaws and other environmental challenges.
7. Identify potential funding mechanisms.
8. Make recommendations to the State Transportation Board as to whether the bypass
warrants additional study.
9. Work with a Technical Advisory Committee (TAC) and interview key stakeholders.
10. Carry out two rounds of public meetings.
ADOT TPD appointed a TAC comprised of Cherie Campbell (PAG), Bob Hazlett (Maricopa
Association of Governments [MAG]), Bill Leister (Central Arizona Association of Governments
[CAAG]), Jermaine Hannon (Federal Highway Administration [FHWA]), and Dale Buskirk
(ADOT TPD) as chairman. Five TAC meetings were held: April 25, June 5, August 14,
September 25, and November 26, 2007.
The study team was asked to proceed immediately with setting up the first round of public
meetings held May 14-17 and with interviews of key stakeholders. An initial set of potential
corridor alternatives was developed based upon ideas provided by the State Transportation Board
and ongoing studies by MAG and PAG, and by ideas provided by the TAC and study team
members. This initial set of alternatives was shown in the public meetings and to the
stakeholders during interviews. The potential alternatives served to generate comments and other
ideas from the public and stakeholders. The research to identify and describe previous and
ongoing studies provided additional ideas for alternative corridors and provided a wealth of
information to be used in refining and evaluating the alternatives.
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Based upon the input from the public and stakeholders, the number of potential alternatives was
reduced and refined and some additional variations were added. This set of alternatives then was
subjected to additional refinement and analysis by the study team to arrive at a refined set of
alternatives that appear to be feasible. Traffic forecasts were prepared for these alternatives.
They were evaluated and documented in this report. Roadway cross sections, cost estimates, and
funding mechanisms were identified.
Preliminary findings were presented to the State Transportation Board at a study session on
November 5, 2007. Further refinements were made and taken to the public in a second round of
public meetings held in November and December. The study findings were presented to the State
Transportation Board on December 21, 2007. Substantial public and agency comments were
received during the study process, through the public meetings and at the Board meeting.
1.3 PREVIOUS AND ONGOING STUDIES
A preliminary list of identified studies was prepared and discussed with the TAC at the April
meeting. Additional studies were added to the list. Through interviews with stakeholders, even
more studies were identified. The final list of studies identified and reviewed is provided in
Appendix A.
1.4 GROWTH SCENARIOS
Over the past few decades, Arizona has been one of if not the fastest growing states in the nation.
It is hard to predict the rate of growth over the next few decades, but many people believe that
the rate of growth will continue at a rapid pace.
The U.S. Census Bureau, Population Division, Interim State Population Projections, 2005 stated
a 2000 population of 5,130,632 and 2030 projections of 10,712,397 for the State of Arizona. This
forecast indicates the population of Arizona will more than double (108.8 percent change) in the
next 25 years.
Information obtained from the Arizona Department of Economic Security, Research
Administration, Population Statistics Unit provides an breakdown of population projections by
Arizona County for the years 2006 and 2030. Ultimate buildout forecast provided by MAG
indicates that Arizona could have 16 million population by 2050.
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2006 2030
Percent
Growth
2006-2030 2050
Percent
Growth
2030-2050
Arizona 6,239,482 10,347,543 65.8% 16,000,000 54.5%
Maricopa 3,764,446 6,207,980 64.9% 9,553,768 53.9%
Pinal 269,892 852,463 215.9% 1,624,774 90.6%
Pima 980,977 1,442,420 47.0% 2,131,150 47.7%
Cochise 134,789 187,725 39.3% 265,388 41.4%
Graham 35,873 44,556 24.2% 62,261 39.7%
Source: Arizona Department of Economic Security for 2006, 2030
Maricopa Association of Governments for 2050
Other studies however, such as the Pinal County Small Area Transportation Study prepared in
2006, estimates the population in Pinal County could be as high as 1,954,016 by 2030. The
Morrison Institute in The Future of Pinal, Making Choices, Making Places indicates that there
are already 650,000 “entitled” housing units in Pinal County, and the county population could be
1,302,950 by 2050. It does appear likely that in the next two or three decades, the population of
Pinal County will be greater than the current population of Pima County. Much of this
population will be centered between the Phoenix and Tucson metropolitan areas and will create
another major urban hub.
The Southeast Arizona Regional Transportation Profile estimates future population in Benson of
78,210 and 19,094 in Willcox. Through a conversation with Graham County staff, they indicated
population projections as high as 100,000 residents in the Safford area.
Figure 1.1 presents a vision of population growth for the State of Arizona as developed by MAG
for 2050. The plan identifies the Arizona Sun Corridor Megapolitan area with the population
concentration reaching from the Prescott area to the Phoenix metropolitan area to the Tucson
metropolitan area to Sierra Vista. This graphic again emphasizes that central Pinal County will
likely greatly exceed what Tucson is today.
Figure 1.1
Arizona Future Growth
I -10 Phoenix-Tucson Bypass Sttudy
Data Source: Maricopa Association of Governments
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1.5 PURPOSE AND NEED
Early in the study process, a purpose and need statement was developed for review by the TAC
at the April meeting. Refinements to the statement were made, and it was shown to the public in
the first round of public meetings and to the stakeholders during the interview process.
The statement shown below is based upon the general need as identified initially by the State
Transportation Board and refined by the study team.
Purpose
• To provide an additional high-capacity transportation corridor to accommodate travel
across southern and central Arizona.
Need
• Provide alternative route to I-10 to relieve traffic congestion on I-10 in the Phoenix and
Tucson metropolitan areas.
• Provide a shorter, faster route through southern and central Arizona that will attract
through trucks and other traffic from I-10.
• Provide a new route that offers an alternative path for I-10 traffic during construction,
maintenance, and incidents.
• Provide a new transportation corridor to serve the expected rapid population growth and
land development in the Sun Corridor.
• Develop a corridor that is context sensitive to environmental and social elements.
If study of this corridor proceeds to the next level of project development, the purpose and need
statement should be refined and more specific needs identified based in part on the findings
included in this report.
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2.0 I-10 EXISTING AND FUTURE CONDITIONS
2.1 EXISTING CONDITIONS
The existing I-10 corridor is one of the major cross-country Interstate routes, serving traffic from
Florida to Los Angeles. The construction of I-10 replaced or used alignments of existing US and
State Highways (US 60, AZ 85, AZ 84, and AZ 86). A section of old US 80 (now I-10) southeast
of Tucson was the first project in Arizona under the Federal Interstate Highway Act. I-10 was
completed through Phoenix in 1990. I-10 provides the main interstate east-west corridor through
Arizona connecting California and New Mexico and serving the bulk of the population and
economic base in Arizona.
The segment of I-10 that is the subject of this study begins west of the junction with SR 85 at
milepost (MP) 98. From there eastward, the route continues through the Phoenix Metropolitan
Area and then takes a southeastward alignment to pass through the Gila River Indian
Community, the communities of Casa Grande, Eloy, and Marana and passes through the Tucson
Metropolitan Area. Continuing eastward, the corridor leads through the City of Benson. The
study corridor terminates east of the City of Willcox at the junction with US 191-MP 356. The
I-10 corridor is approximately 258 miles in length and provides mobility on an interstate, intra-state,
small urban and large urban scale. Based on the wide variety of built, agricultural, and
natural environment, the characteristic and function of the corridor vary widely.
Table 2-1 presents an overview of the existing number of lanes (based on the 2005 Highway
Performance Monitoring System [HPMS] data set). The existing number of lanes vary from
4 through lanes in primarily rural areas to sections with 10 and 12 lanes within the Phoenix
Metropolitan Area. Similarly, existing traffic volumes range from about 25,000 vehicles per day
(vpd) west of SR 85 to almost 300,000 vpd in the Phoenix Metropolitan Area. Traffic volumes
reduce to about 40,000 vpd at the intersection with Interstate 8 (I-8) near Casa Grande and
increase to about 160,000 vpd in Tucson. At the east end of the corridor, approximately
14,000 vpd are recorded.
Figure 2.1 illustrates the traffic volumes and truck percentages in the study corridor. In rural
areas, trucks account for up to 45 percent of traffic volumes while within the metropolitan areas
truck percentages are much lower due to the overall high traffic volumes. The recently available
2006 traffic counts were reviewed and compared to 2005 counts. For the most part, there was an
increase in volumes in most places. Due to daily fluctuations in traffic, counts need to be
compared over several years to establish trends.
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Table 2-1 I-10 2005 Average Daily Traffic and Number of Through Lanes
Milepost West of Cross Road
2005
Through
Lanes
Existing
Volume
(2005)
Existing
Truck %
103.45 SR 85 4 25,000 36%
124.5 Loop 303 4 72,000 29%
132.12 Dysart Road 4 176,000 15%
134.03 Loop 101 6 123,000 28%
136.70 75th Avenue 10 137,000 11%
144.7 7th Avenue 12 281,000 11%
145.7 7th Street 10 285,000 11%
146.96 SR 51 12 285,000 11%
148.9 Buckeye Road 8 230,000 11%
150.01 24th Street 12 296,000 11%
151.47 University Drive 10 291,000 11%
155.83 US 60 10 206,000 11%
157.77 Elliot Road 8 152,000 35%
161.10 Chandler Boulevard 6 91,000 35%
161.2 Loop 202 6 91,000 35%
164.5 Queen Creek Road 4 87,000 35%
169 Riggs Road 4 47,000 35%
199.16 I-8 4 37,000 34%
240.74 Tangerine Road 6 48,000 38%
247.25 Cortaro Road 4 82,000 38%
260.39 I-19 6 156,000 21%
268.7 Craycroft Road 6 49,100 21%
270.87 Kolb Road 4 53,000 17%
302.7 SR 90 4 25,400 45%
352.2 US 191 4 14,000 45%
Source: ADOT Highway Log, 2005 HPMS
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Figure 2.1 2004 Traffic Volumes and Truck Percentage
2.2 PLANS FOR IMPROVING I-10
Indicative of the high development pressure and the associated mobility needs within the study
corridor, a multitude of transportation studies were recently completed, are currently under way,
or are planned to start in the near future. Appendix A provides a list and summary of relevant
studies.
Local Transportation Studies: Studies such as Small Area Transportation Studies (SATS) help
local jurisdictions define transportation needs and systems ranging from individual cities and
towns to county-wide efforts such as the Pinal County SATS. In most cases, a SATS establishes
travel demand forecasts for the area under study.
Regional Studies: On a regional scale, ADOT uses a variety of study formats to examine the
needs and deficiencies on the State Highway System. These studies may encompass multiple
counties and jurisdictions. One example is the currently ongoing Southern Pinal/Northern Pima
Corridor Definition Study that will establish a list of prioritized highway projects for the area
between the Phoenix and Tucson metropolitan areas. Next to establishing future forecasts, the
study will also look at the possibility of additional capacity needs besides what can be
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accomplished through improvements to the existing State Highway System. New high capacity
corridors will be identified.
Identification of new corridors in the metropolitan areas is also undertaken by the respective
metropolitan planning organizations (MPOs). MAG recently initiated a series of “Regional
Framework studies” such as the I-10 Hassayampa and Hidden Valley framework studies that
look beyond the traditional 20-year planning horizon identifying needed high-level facilities
based on build-out forecasting. The Pima Association of Governments (PAG) is in the process of
concluding the PAG Loop Road Study assessing the potential for freeway facilities in the Tucson
area. The MPOs are also sources of travel-related statistics and forecasts such as the MAG:
Phoenix External Travel Survey (2001) and the 2006 Freeway Level of Service Study.
Statewide Studies: Several studies are currently under way that examine multi-modal mobility
needs. URS is preparing the Commuter Rail Study for MAG and is a part of the team that
provided an update of a study of High-Speed Rail between Phoenix and Tucson. Wilbur Smith
Associates (WSA) will be starting the Arizona Freight Study. ADOT has recently launched a
major effort to to update the 2005 MoveAZ Statewide Transportation Plan.
National and Other Pertinent Studies: The national I-10 Freight Study (conducted by WSA)
analyzed the multi-modal transportation needs for I-10 and developed a plan for improvements
to the interstate corridor.
Corridor Specific Studies: In addition, ADOT undertook a series of corridor specific studies
such as the Pinal County Corridor Definition Studies evaluating the need for additional high-capacity
corridors in Northern Pinal County. ADOT is also conducting a series of corridor
studies on I-10 as described below:
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I-10 Corridor Study: SR 51/Piestewa to Loop 202/Santan Freeway Corridor Improvement
Study
A Corridor Improvement Study (CIS) is currently under
way to evaluate freeway improvement alternatives along
I-10 from SR 51 to Loop 202. Alternatives being evalu-ated
include the addition of local and express access routes
in the study area. Preliminary findings call for up to
24 lanes in sections of the study corridor.
I-10 Corridor Study: I-8 to Loop 202 Corridor Study
The I-10/I-8 to Loop 202 Corridor Study is just getting
under way and will examine deficiencies and needs for the
I-10 corridor between Casa Grande and Chandler. One
issue the study will discuss is I-10 location on a perpetual
easement through the Gila River Indian Community. The
easement is defined in a lease agreement between the Gila
River Indian Community, ADOT, the Bureau of Indian
Affairs (BIA), and Federal Highway Administration dated
1966. The lease agreement included concepts for the
roadway cross-section that will be discussed among the
stakeholders and will be evaluated in the upcoming
corridor study. One issue is that some of the concepts developed in 1966 are not in compliance
with current roadway design standards. One of the objectives of the study is to analyze an
interim widening of I-10 and will look at the feasibility to continue the cross-section defined in
the I-10 Corridor Study I-8 to Tangerine Road with 10 lanes with two frontage roads from I-8 to
Loop 202. The study will rely on travel demand modeling from MAG and has requested model
assignments.
I-10 Corridor Study: Tangerine to I-8 Corridor Study
The I-10 Tangerine to I-8 corridor study is studying long-term improvements for 41 miles of
I-10, between I-8 at MP 199 in Casa Grande and Tangerine Road at MP 240 in Marana. The
study determined an ultimate cross-section of 10 lanes with two-lane frontage roads by 2030. A
total right-of-way of between 430 and 500 feet will be needed to accommodate the facility. The
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study effort developed a travel demand forecast for the I-10 corridor. Results of the forecast
indicate that travel demand will far exceed what can be accommodated by the improved I-10
corridor. In sections north of Tucson, more than 400,000 vpd are forecasted. Capacity for excess
demand is assumed to be provided by additional facilities such as the potential Phoenix-Tucson
bypass.
Since future traffic volumes are expected to exceed the current capacity of the I-8/I-10
interchange, the development of a long-range plan (2030) for the I-8 interchange area has been
added to the I-10 corridor study.
I-10 Corridor Study: I-19 to the Pima/Cochise County Line
The purpose of the I-10 Corridor Study is to identify transportation needs and transportation
deficiencies and to develop recommendations for corridor rehabilitation to meet multimodal
transportation demands in the year 2030 along approximately 37 miles of I-10 from I-19 to the
Pima/Cochise County line. The I-10 Corridor Study involves the development of planning
studies, engineering analyses, an environmental overview, and planning-level transportation
road-way design. Study recommendations are intended for use by ADOT to program interstate
rehabilitation, preserve right-of-way, manage corridor land uses, and protect access control.
Summary of Currently Proposed Lanes on I-10
Table 2-2 presents an estimate of planned number of lanes as identified by the various regional
travel demand models and corridor specific models.
Table 2-2 Estimate of Planned Number of Lanes and 2030 Model Volumes
Milepost West of Cross Road
2030 AADT
(000’s)
2030
Lanes Agency/Study
113.0 SR 85 128 6 MAG
124.5 Loop 303 164 6 MAG
132.12 Dysart Road 232 10 MAG
134.03 Loop 101 280 12 MAG
136.70 75th Avenue 280 12 MAG
144.7 7th Avenue 296 12 MAG
145.7 7th Street 341 10 MAG
146.96 SR 51 340 12 MAG
148.9 Buckeye Road 186 8 MAG
150.01 24th Street 326 12 MAG
151.47 University Drive 412 17 MAG
155.83 US 60 427 22 MAG
157.77 Elliot Road 247 10 MAG
161.10 Chandler Boulevard 196 10 MAG
161.2 Loop 202 195 10 MAG
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Milepost West of Cross Road
2030 AADT
(000’s)
2030
Lanes Agency/Study
164.5 Queen Creek Road 127 8 MAG
169 Riggs Road 123 6/ Pinal SATS/
8 MAG
199.16 I-8 104 10 I-10 DCR
6 Pinal SATS
4 MAG
240.74 Cortaro Road N/A 10 I-10 DCR
6 Pinal SATS
247.25 Tangerine Road 415 10 I-10 Design Concept
Report (DCR)
160 8 PAG
260.39 I-19 198 8 PAG
265.3 Alvernon Way 95 8 I-10 Southeast CS/ PAG
270.87 Kolb Road 100 10 I-10 Southeast CS/ PAG
275.7 Houghton Road 100 8 I-10 Southeast CS/ PAG
302.7 SR 90 N/A 6 I-10 Southeast CS/ PAG
352.2 US 191 N/A 4
Programmed Projects
ADOT has programmed the following projects within the Phoenix Area. The lanes added are for
each direction of travel.
• Verrado Way to Sarival Avenue: Add one general purpose lane in median
• Sarival Avenue to Dysart Road: Add high-occupancy vehicle (HOV) lane and two
general purpose lanes
• Dysart Road to Loop 101: Add HOV and one general purpose lane
• Loop 101 to I-17 – Phase 1: Add general purpose lane
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Figure 2.2 MAG I-10 Improvements
ADOT has identified four interim improvement project to widen I-10 between Tangerine Road
and I-8 to three lanes in each direction and construction is expected to start in 2008. The four
sections are: I-8 to SR 87, SR 87 to Picacho Peak Road, Picacho Peak Road to Pinal Air Park,
and Pinal Air Park to Tangerine Road.
2.3 PLANS FOR IMPROVEMENTS TO OTHER HIGHWAYS
2.3.1 US 70
Approaching Arizona from New Mexico on I-10, an alternative route is US 70 from Lordsburg
to Globe and US 60 from Globe to Phoenix. Substantial improvements to US 70 could make this
a viable alternate route from Lordsburg to the Phoenix metropolitan area. For the most part,
US 70 is a two-lane rural highway and would require widening and major improvements.
Portions of the route traverse rugged terrain; other portions are located within the San Carlos
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Indian Reservation. Generally, this alternative route could serve as a bypass of Tucson for traffic
destined between New Mexico and Phoenix or northern Arizona. In recent years, US 70 was
widened to a five-lane urban cross-section through the communities of Pima, Thatcher, and
Safford. In addition, ADOT is currently improving the Gila River Bridge at Bylas on US 70.
ADOT is also studying a potential realignment of US 191 and US 70 in the Safford area.
2.3.2 US 60
ADOT has completed preliminary feasibility studies for substantial improvement to US 60
between Superior and Globe through the rugged mountainous and mining area. Design concept
and environmental studies will begin later this year. The highway is currently operating at a poor
level of service (LOS), and crashes occur at a high rate and severity. US 60 serves as a critical
link between the Phoenix Metropolitan Area and the east-central portions of Arizona, providing
access to several national forest recreation areas and the White Mountain Apache Indian
Reservation. The highway also serves as a commercial link to several towns and communities
including Superior and the Globe-Miami area. US 60 also connects to US 70 east of Globe,
which leads to Safford and could serve as an alternate route for I-10 traffic from Lordsburg to
Phoenix, bypassing Tucson. However, several of the preliminary alternatives for the study focus
on bypassing the Miami-Globe area to the north favoring connectivity of the US 60 route. If this
occurs, direct connectivity of the US 60 to US 70 would be diminished.
2.3.3 US 191
ADOT has widened a substantial portion of US 191 between I-10 and US 70 in Safford to a four-lane
divided highway. Portions currently remain as a two-lane rural highway. ADOT is
completing the design to widen US 191 between MP 91.80 and MP 94.34, just north of I-10.
Design concept and environmental studies are under way to complete the widening and possible
realignment of US 191 through the south Safford area to connect with US 70.
2.3.4 I-8
Currently there are no plans for improvements to the I-8 corridor. Pinal County suggests that I-8
be planned for 10 lanes and frontage roads and is requesting developers preserve the right-of-way.
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2.3.5 SR 85
Together with I-8, SR 85 is the official truck bypass route around metropolitan Phoenix and has
also been designated as the CANAMEX corridor as part of the North American Free Trade
Agreement (NAFTA). In addition to serving as the I-10 bypass, this corridor also metropolitan
Phoenix to I-8 which leads to Yuma and San Diego. An ADOT DCR and subsequent Access
Management Study identified 12 interim corridor segments that ultimately will construct two
additional lanes to provide a continuous four-lane divided highway from I-8 in Gila Bend to I-10
in Buckeye. These interim corridor segment improvements make up the first phase toward the
ultimate goal of a fully access controlled highway. Construction of all sections, except the bypass
of Gila Bend, is expected to be completed by 2010.
ADOT is currently preparing a DCR for a fully access controlled-facility that will connect SR 85
to I-8 near Gila Bend. No alternative has been selected yet. The study is currently evaluating
feasible alternatives for this connection.
2.3.6 South Mountain Freeway
The planned South Mountain Freeway would extend SR 202L from I-10 near Pecos Road
westward around South Mountain and reconnect with I-10 in the vicinity of 51st Avenue. This
project is included in the MAG RTP and in the Proposition 400 funding program. An
Environmental Impact Statement (EIS) is being prepared. Funding is included in Phases I and II
of the MAG plan. Completion of this roadway would offer an alternative route to I-10 for the
most congested portion in Phoenix and Tempe.
2.3.7 I-10 Reliever
SR 801, also known as the I-10 Reliever, is a planned state highway in the southwest portion of
the Phoenix metropolitan area. It will connect the southern terminus of Loop 303 with the South
Mountain leg of Loop 202. It is planned as a controlled-access freeway to relieve heavy traffic
congestion experienced along I-10 in the area. Although no construction has begun for the route,
planning documents have identified a study area running roughly 5 miles south of and parallel to
I-10 through largely undeveloped land. In addition to reducing commuter traffic on I-10, SR 801
will serve the industrial and warehouse district in southwest Phoenix, and particularly the truck
traffic generated by this district.
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URS Job No. 23445042
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2.4 OTHER MODES
2007 Review of the 1998 Arizona High-Speed Rail Study
ADOT undertook a review of the 1998 Arizona High-Speed Rail Study, assessing rail options in
the Phoenix-Tucson Corridor. The 1998 study forecasted 2020 daily traffic of 51,000 vehicles on
I-10 near the I-8 interchange. Of the total number of vehicles, 25 percent was estimated to be
commercial vehicles. The study contained four alternatives for high-speed rail which varied in
speed and costs. The four alternatives are:
• Alternative 1, Conventional Rail – Minor Upgrade
• Alternative 2, Conventional Rail – Major Upgrade
• Alternative 3, High-Speed Rail – Electric
• Alternative 4, High-Speed Rail – Magnetic Levitation
The 1998 study contained a reduction of daily travel on I-10 of 2,750 vehicles for Alternative 1,
5,300 vehicles for Alternative 2, 6,000 vehicles for Alternative 3, and 6,500 vehicles for
Alternative 4. This equates to reductions ranging from 5 percent to 13 percent of the 2020 daily
traffic on I-10.
In the 2007 update, the 2020 projection of traffic on I-10 was increased to 58,000 vpd. The
projection of the percentage of commercial vehicles was also increased to 37 percent of the total
traffic per ADOT provided data. The higher truck percentage indicates that truck traffic is
expected to increase faster than all traffic. The 2007 report concluded that the 1998 study high-speed
rail usage estimates appear to provide a reasonable order of magnitude.
Commuter Rail Strategic Plan
MAG is conducting the Commuter Rail Strategic Plan (CRSP) for Maricopa County and
northern Pinal County. The MAG 2003 High Capacity Transit Study provides a strong
foundation for the Strategic Plan. Goals of the study are to:
• Assess local and regional support for commuter rail
• Identify and evaluate issues related to implementation, such as funding, governance and
administration, environmental issues, land use and sprawl, capacity constraints, and other
issues
Final Report
I-10 Phoenix-Tucson Bypass Study
Arizona Department of Transportation
2-12
January 2008
URS Job No. 23445042
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• Develop a methodology for evaluating potential commuter rail corridors
• Establish and gain consensus for an implementation strategy and plan
2.5 2030 TRAFFIC FORECASTS
Based on existing studies and forecasts, most of the existing and future roadways and freeways
in the Phoenix and Tucson metropolitan areas will not be able to provide sufficient capacity to
accommodate future travel demand. Similarly, if growth trends continue, much of central Pinal
County will be underserved by major transportation routes. As outlined in Table 2-2 of Estimate
of Planned Number of Lanes and 2030 Model Volumes, 2030 traffic volumes on I-10 in the
Phoenix Area are projected to exceed 400,000 vpd even with all the Proposition 400 projects in
place at that time. Similarly, existing I-10 in Tucson will approach 200,000 vpd with currently
planned improvements in place. Traffic forecasts for the I-10 segment between Tucson and
Phoenix vary considerably among studies and forecasts. The forecasts developed as part of this
study estimate approximately 100,000 vpd on I-10 between the two major metropolitan areas.
As part of this I-10 Bypass Study traffic forecasts were made and are described in more detail in
Chapter 5 and in a technical memorandum included in the Appendix. Table 5-1 provides a
summary of the forecast. The overall bypass corridor was divided into the west segment and the
east segment. There are two alternatives for the east segment one that would go north of Tucson
and intersect I-10 near Willcox and the other that would go west and south of Tucson and
intersect I-10 near SR 83 east of Tucson.
The three corridor concepts were tested to identify the relief they would provide on the I-10
corridor as well as how much traffic they would carry. The traffic forecast on the bypass corridor
consists of long-trips and through traffic only. Traffic that may be generated by urban
development that may occur along the corridor is not included in the estimate.
The West Segment could potentially carry at least 53,000 vpd in 2030 and relieve the existing
I-10 in the Phoenix area by more than 44,000 vpd. The I-10 East Segment (west and south of
Tucson) would carry over 39,000 vpd in 2030, relieving traffic on I-10 through the Tucson area
by almost 33,000 vpd. The East Segment (north of Tucson) would be used by at least 17,500 vpd
in 2030 resulting in a potential decrease of 14,500 vpd on I-10 in the Tucson Area. If both the
East Segment options are constructed, the reduction in traffic on I-10 in Tucson would be
40,000 vpd in 2030.
Final Report
I-10 Phoenix-Tucson Bypass Study
Arizona Department of Transportation
2-13
January 2008
URS Job No. 23445042
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2.6 NEED FOR BYPASS
The foregoing information provides a basis to make a preliminary assessment of the need for a
new corridor that would serve as a bypass for I-10 in the Phoenix and Tucson metropolitan areas.
I-10 in Phoenix is congested today, and ADOT has programmed several projects that will add
lanes to I-10 through the entire metropolitan area. Construction on some of the widening is
scheduled to begin later in 2007. In addition, the MAG RTP includes the South Mountain
Freeway and SR 801 (I-10 Reliever) and Proposition 400 provides some of the funding needed
for these new routes. The two new routes are designed to offer relief and alternative routes to
I-10 in the Phoenix area; however, the 2030 forecast prepared by MAG indicates that even with
these additional routes and light-rail transit, I-10 is expected to carry the maximum load possible
which means there will be peak-hour congestion. Peak-hour congestion seems inevitable in a
metropolitan area of 6 million people.
SR 85 and I-8 is the designated I-10 bypass route for the Phoenix metropolitan area. When SR 85
is completed as a four-lane access controlled highway, this bypass route should serve this
function for many years to come. Urban growth expected in the Tonopah Valley-Buckeye-
Goodyear-Maricopa area will not be served well by SR 85 and I-8 because the Sonoran Desert
National Monument separates the potential urban development from these routes. Accordingly,
additional routes may be needed to serve the future urban growth in the area.
The SR 85/I-8 bypass is slightly longer than staying on I-10 (approximately 5 miles longer).
When SR 85 is completed, it will provide a route where constant high speeds can be maintained
so that it will serve well as a bypass route for several years.
I-10 in Tucson will be widened to provide four lanes in each direction. Additional widening is
not likely because of the major impacts that would occur to adjacent land uses. The projected
2030 traffic volumes of up to 200,000 vpd indicate that peak-hour congestion will be the norm in
Tucson.
I-10 is the only east-west route that passes through southern Arizona. US 191-US 70-US 60
offers an alternative route for traffic entering Arizona from New Mexico and wanting to go to
Phoenix. Improvements to US 70 through the San Carlos Apache Indian Reservation are not
likely to occur. US 60 is limited as a truck route because it passes through very rugged
mountainous terrain. Since this route connects into the freeway system in the greater Phoenix
area, it would not serve interstate (New Mexico to California) traffic very well.
Final Report
I-10 Phoenix-Tucson Bypass Study
Arizona Department of Transportation
2-14
January 2008
URS Job No. 23445042
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Given the expected worsening traffic congestion in Tucson and the absence of a suitable
alternative route, there appears to be a need to further consider bypass alternatives for I-10 in
southern Arizona.
The dramatic growth in truck traffic in Arizona and throughout the nation has created a major
challenge to the nation’s highway system. Similarly, the growth in rail freight has overwhelmed
the railroad industry. Union Pacific Railroad (UPRR), which roughly parallels I-10 and I-8
through Arizona, is undergoing major upgrades to provide double tracks from El Paso to Los
Angeles. A major new rail yard is currently planned near I-10 in southern Pinal County. Even
with the improvements to the rail system, substantial increases in truck traffic appear likely. The
percentage of the total number of vehicles on I-10 that are heavy trucks (outside the two major
metropolitan areas) is already 30 to 50 percent and could go higher.
With the expected urban growth in central Pinal County, I-10 will essentially become an urban
freeway from west of SR 85 to east of Tucson. This means that interstate traffic on I-10
(including many trucks) will be subjected to the typical urban peak-hour congestion for
150 miles in Arizona. This situation would cost everyone hundreds of dollars per year in lost
time and increased cost of goods and services due to increased travel time. The total reliance on
one major route through southern Arizona places a huge risk that a crash, construction, or major
event could shut down the main lifeline to 80 percent of the population in Arizona.
Final Report
I-10 Phoenix-Tucson Bypass Study
Arizona Department of Transportation
3-1
January 2008
URS Job No. 23445042
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3.0 POTENTIAL NEW CORRIDORS
3.1 INITIAL POTENTIAL CORRIDOR ALTERNATIVES
In January 2007, an article appeared in the Tucson Citizen regarding the need for an I-10
Phoenix-Tucson bypass. That article contained a graphic that showed a potential corridor starting
at I-10 west of SR 85 and running generally southeastward and crossing I-8 west of Casa Grande
and crossing I-10 in Pinal County south of the I-8 junction. The corridor continued eastward and
then southeastward in the San Pedro Valley to rejoin I-10 at one of several potential connection
points between Willcox and Benson. This initial corridor illustrated the basic concept as
envisioned by the State Transportation Board when the study was initiated. This basic corridor
idea was included in the Request for Proposals issued by the Transportation Planning Division.
From this initial idea, several other initial potential corridors were identified. These ideas were
presented to the TAC on April 25, 2007, for concurrence that they were suitable to show to the
public and stakeholders in the series of meetings and interviews conducted in May and June.
This initial set of corridors did provide a basis for the public and stakeholders to understand the
scope and intent of the bypass and to provide more specific reaction to the various ideas.
In order to develop the initial potential corridors, the major fatal flaw constraints were identified
through existing geographic information system (GIS) databases. Four constraints maps were
prepared as shown in Figure 3.1 through Figure 3.4. The first shows major environmental
constraints including preserved lands (National forests, monuments, parks, wilderness areas;
areas of critical environmental concerns, faults, rivers, Central Arizona Project [CAP] Canal).
These data have been refined during the course of this study.
The potential corridors were laid out to avoid the preserved areas and to minimize crossings of
other highways, streams and railroads. These data were refined during the course of the study.
The second figure shows land ownership (or the agency that manages the surface of the land).
Indian Reservation Land was avoided. Bureau of Land Management (BLM) land was avoided
where possible. State Trust Lands are for future development so they were viewed as
opportunities for potential location of a new corridor. The third figure shows the major
topographic features. Most of these features coincide with the preserved land identified in
Figure 3.1. Figure 3.4 shows the major existing highways and railroads to provide a basis for
looking at what connections may be made with a new potential future corridor.
South
Maricopa Mtns.
Wilderness
Table Top
Wilderness
Sonoran Desert
National Monument
Picacho Peak
State Park
Ironwood Forest
National Monument
Coyote Mtns.
Wilderness
Baboquivari
Peak
Wilderness
San Pedro Valley
West Saguaro
Wilderness
Saguaro National
Park
Catalina
State
Park
Pusch
Ridge
Wilderness
Oracle
State
Park
Aravaipa
Canyon
Wilderness
Santa Teresa
Wilderness
North Santa Teresa
Wilderness
Galiuro
Wilderness
Dos Cabezas
Mountains
Wilderness
Saguaro National
Park Rincon
Mountain District
East
Saguaro
Wilderness
Rincon
Mountain
Wilderness
North
Maricopa Mtns.
Wilderness
Big Horn Mountains
Wilderness
Tonto National Forest
Woolsey Peak
Wilderness
Sierra Estrella
Wilderness
Superstition
Wilderness
Kartchner
Caverns
State Park
Chiricahua
Wilderness
Fishooks
Wilderness
Organ Pipe
National Monument
and Wilderness
Cabeza Prieta
National
Wildlife
Refuge
and
Wilderness
Blue Ridge
Primitive
Wilderness
Aravaipa Valley
Casa Grande
National Monument
Coronado
National
Forest
Coronado
National
Forest
Coronado
National
Forest Hot Springs Canyon
Copper Creek
Cooks Lake
Three Links Farm
Pinaleno
Mountains
Willcox
Playa
Winchester
Mountains Sulphur
Springs
Valley
Allen
Flat
Proposed
Park
Cactus
Forest
Tortolita
Mountain
Park
Avra
Valley
Buehman
Wet Lands
Proposed
Park
White Tanks Mountains
Regional Park
South Mountain
Park
Palo Verde
Mountains
Haley Hills
Santan Mountains
Regional Park
Pima County
Fair Grounds
Coronado
National Forest
Coronado
National Forest
Fort Bowie
National
Historic Site
Peloncillo Mountains
Wilderness
Gila Box Riparian
National Conservation
Area
Bear Springs
Badlands
Needles Eye
Wilderness
Coffee Pot
Ajo Regional Mountain
Park
Desert
Grasslands
Tucson
Mountain
Park
Tucson Mitigation
Corridor
TUCSON
BENSON
WILLCOX
SAFFORD
MARANA
ELOY
CASA GRANDE
COOLIDGE
FLORENCE
GLOBE
MARICOPA
GILA BEND
PHOENIX
MESA
BUCKEYE
GOODYEAR
TOHONO O'ODHAM NATION
SAN CARLOS APACHE
INDIAN RESERVATION
SAN XAVIER
Santa Cruz River
San Pedro River
Gila River
Gila River
Santa Cruz River
Salt River
Gila River
CAP CANAL
SUPERIOR
Legend
Study Area
CAP Canal
Major Rivers
City Limits
Area of Critical Environmental Concern
Wilderness Areas
National Monuments
Forest / Parklands / Other Conservation Areas
Figure 3.1
Environmental Constraints
II--10 Phoeniix--Tucson Bypass Sttudy
Data Source: ALRIS 1997 - 2005, Bureau of Land Management, ADOT ATIS 2005, ADOT HPMS 2005, USGS, Bureau of Transportation Statistics
0 2.5 5 10 15 20
Miles
Scale Data Source: ALRIS 1997 - 2005, Bureau of Land Management,
ADOT ATIS 2005, ADOT HPMS 2005, USGS,
Bureau of Transportation Statistics
P:\TRANSPORTATION\ADOT_TPD\23445042_I-10_Phx_Tucson_Bypass_Study\Docs\Final Reports\Figures\Fig3_1_Envi_Constraints.pdf (ai)
Disclaimer:
While every effort has been made to ensure the accuracy
of this information, the Arizona Department of Transportation
makes no warranty, expressed or implied as to its accuracy
and expressly disclaims liability for the accuracy thereof.
Figure 3.2
Land Ownership
TUCSON
BENSON
WILLCOX
SAFFORD
MARANA
ORO VALLEY
ELOY
CASA GRANDE
COOLIDGE
FLORENCE
GLOBE
MARICOPA
GILA BEND
PHOENIX
MESA
BUCKEYE
GOODYEAR
TOHONO O'ODHAM NATION
SAN CARLOS APACHE
INDIAN RESERVATION
SAN XAVIER
WHITE MOUNTAIN APACHE
Legend
BLM
U.S. Forest Service
National Park Service
USFWS National Wildlife Refuge
American Indian Res.
Military
State Trust
Local or State Parks
Other; Private
City Limits
I -10 Phoenix-Tucson Bypass Sttudy
Data Source: ALRIS 1997 - 2005, Bureau of Land Management, ADOT ATIS 2005, ADOT HPMS 2005, USGS, Bureau of Transportation Statistics
0 2.5 5 10 15 20
Miles
Scale Data Source: ALRIS 1997 - 2005, Bureau of Land Management,
ADOT ATIS 2005, ADOT HPMS 2005, USGS,
Bureau of Transportation Statistics
P:\TRANSPORTATION\ADOT_TPD\23445042_I-10_Phx_Tucson_Bypass_Study\Docs\Final Reports\Figures\Fig3.2_LandOwnership.pdf (ai)
Disclaimer:
While every effort has been made to ensure the accuracy
of this information, the Arizona Department of Transportation
makes no warranty, expressed or implied as to its accuracy
and expressly disclaims liability for the accuracy thereof.
TUCSON
BENSON
WILLCOX
SAFFORD
MARANA
ORO VALLEY
ELOY
CASA GRANDE
COOLIDGE
FLORENCE
GLOBE
MARICOPA
GILA BEND
PHOENIX
MESA
BUCKEYE
GOODYEAR
TOHONO O'ODHAM NATION
SAN CARLOS APACHE
INDIAN RESERVATION
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Figure 3.3
Topography
Legend
I -10 Phoenix-Tucson Bypass Sttudy
Data Source: ALRIS 1997 - 2005, Bureau of Land Management, ADOT ATIS 2005, ADOT HPMS 2005, USGS, Bureau of Transportation Statistics
0 2.5 5 10 15 20
Miles
Scale Data Source: ALRIS 1997 - 2005, Bureau of Land Management,
ADOT ATIS 2005, ADOT HPMS 2005, USGS,
Bureau of Transportation Statistics
P:\TRANSPORTATION\ADOT_TPD\23445042_I-10_Phx_Tucson_Bypass_Study\Docs\Final Reports\Figures\Fig3.3_Topography.pdf (ai)
Shaded Relief
Contour Line (1,000' Interval)
Major Roads
City Limits
0 - 1,000 ft
1,000 - 2,600 ft
2,600 - 4,200 ft
4,200 - 5,500 ft
5,500 - 6,800 ft
6,800 - 12,598 ft
Disclaimer:
While every effort has been made to ensure the accuracy
of this information, the Arizona Department of Transportation
makes no warranty, expressed or implied as to its accuracy
and expressly disclaims liability for the accuracy thereof.
TUCSON
BENSON
WILLCOX
SAFFORD
MARANA ORO VALLEY
ELOY
CASA GRANDE
COOLIDGE
FLORENCE
GLOBE / MIAMI
GILA BEND
PHOENIX
MESA
BUCKEYE
GOODYEAR
TOHONO O'ODHAM NATION
SAN CARLOS APACHE
INDIAN RESERVATION
SAN XAVIER
PIMA
COCHISE
GRAHAM
PINAL
GILA
MARICOPA
GREENLEE
APACHE
Union Pacific RR
Cooper Basin RY
Arizona Eastern Railway
Union Pacific RR
Union Pacific RR
San Manuel
Arizona RR
Tucson-Cornelia &
Gila Bend RR
SELLS
RYAN FIELD
TUCSON INTL
BENSON MUNICIPAL
SAN MANUEL
PINAL AIRPARK
MARANA REGIONAL
KEARNY
ELOY MUNI
CASA GRANDE MUNI
PHOENIX REGIONAL
GILA BEND MUNI
CHANDLER MUNI
PHOENIX SKY HARBOR INTL
LOST DUTCHMAN
SAN CARLOS APACHE
BUCKEYE MUNI
PHOENIX GOODYEAR
SAFFORD REGIONAL
AJO MUNI
SUPERIOR MUNI
FALCON FIELD
GLENDALE
Figure 3.4
Existing Transportation System
Legend
I -10 Phoenix-Tucson Bypass Sttudy
Data Source: ALRIS 1997 - 2005, Bureau of Land Management, ADOT ATIS 2005, ADOT HPMS 2005, USGS, Bureau of Transportation Statistics
0 2.5 5 10 15 20
Miles
Scale Data Source: ALRIS 1997 - 2005, Bureau of Land Management,
ADOT ATIS 2005, ADOT HPMS 2005, USGS,
Bureau of Transportation Statistics
P:\TRANSPORTATION\ADOT_TPD\23445042_I-10_Phx_Tucson_Bypass_Study\Docs\Final Reports\Figures\Fig3.4_Transportation.pdf (ai)
Railroads
Major Roadways
Local Roads
City Limits
Airports
Disclaimer:
While every effort has been made to ensure the accuracy
of this information, the Arizona Department of Transportation
makes no warranty, expressed or implied as to its accuracy
and expressly disclaims liability for the accuracy thereof.
Final Report
I-10 Phoenix-Tucson Bypass Study
Arizona Department of Transportation
3-6
January 2008
URS Job No. 23445042
P:\TRANSPORTATION\ADOT_TPD\23445042_I-10_Phx_Tucson_Bypass_Study\Docs\Final Reports\Final Report\I-10 Bypass Study Final Report 01-2008.doc
The initial set of potential corridor alternatives is shown in Figure 3.5. This graphic was
presented in the public meetings held in May and was shown to the stakeholders during the
interviews. The alternatives included existing highways that do or could serve as an alternative to
I-10, planned/proposed freeway corridors from the MAG, CAAG, and PAG planning processes,
and corridors that someone had suggested or that the project team thought had merit based upon
a quick review of various major constraints features that were identified from the available
statewide GIS data sources.
During May and June, the project staff interviewed staffs of 28 stakeholder agencies. These
stakeholders included most of the cities and counties that might be affected by the potential
bypass and many special purpose groups and organizations that expressed interest in the project.
The Arizona State Land Department and the Arizona Game and Fish Department were
interviewed as well. The interview process is described more fully in Chapter 8.
The response from the individual stakeholder agencies is shown in Table 3-1 and combined in
Table 3-2. In general the stakeholders indicated support for the bypass idea and specifically for
initial potential corridor alternatives C, F/M, and H. In general most of the cities and counties
expressed support for the bypass. Most of the specialized environmental organizations oppose
the bypass with strong opposition to corridor K. In this summary, corridor K is used to represent
all alternatives in the San Pedro Valley. Other stakeholders expressed support for corridors C, H,
K, and M.
Tohono O'odham Nation
San Carlos Apache
Indian Reservation
Tucson
Marana
Eloy
Casa Grande
Phoenix
Florence
Coolidge
Gila Bend
Willcox
Benson
San Xavier
Gila River
Indian Community
E
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G
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H
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K
M
D
N
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B
O
J
A
E
L
Figure 3.5
Initial Potential Corridors
Legend
I -10 Phoenix-Tucson Bypass Sttudy
Data Source: ALRIS 1997 - 2005, Bureau of Land Management, ADOT ATIS 2005, ADOT HPMS 2005, USGS, Bureau of Transportation Statistics
0 2.5 5 10 15 20
Miles
Scale Data Source: ALRIS 1997 - 2005, Bureau of Land Management,
ADOT ATIS 2005, ADOT HPMS 2005, USGS,
Bureau of Transportation Statistics
P:\TRANSPORTATION\ADOT_TPD\23445042_I-10_Phx_Tucson_Bypass_Study\Docs\Final Reports\Figures\Fig3.5_Initial_Corridors.pdf (ai)
A
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D
E
F
G
H
I
J
K
L
M
N
O
Potential Corridor Segments
Final Report
I-10 Phoenix-Tucson Bypass Study
Arizona Department of Transportation
3-8
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Table 3-1 Initial Stakeholder Responses to Potential Corridor Alternativesa
Support Bypass
Concept
Support Potential
Corridorsb
Avoid Potential
Corridorsb
Cities
1 Benson Y H, K
2 Buckeye Y N
3 Casa Grande Y F, M, K
4 Eloy Y MKB, H-C E
5 Gila Bend Y G, K C
6 Goodyear Y G
7 Marana Y H-C
8 Maricopa Y C, F E
9 Oro Valley Y CMKB OR CFKB,
C-H
10 Safford Not Completed
11 Tucson Y H K
12 Willcox Not completed
Counties
13 SEAGO Y L K
14 Cochise Y G-M
15 Graham Y F
16 Maricopa Y C-I-K E
17 Pima Y/Nc K
18 Pinal Y ABK E,L
Other
19 Arizona State Land Dept No preferences
20 Arizona Game and Fish Dept N H(I-19 to I-10 E) C,K,L,D,B,A,J
21 Center for Biological Diversity Not completed
22 Drachman Not completed
23 Morrison Institute No preferences
24 Nature Conservancy N E K,L,C
25 Pinal Partnership Y
26 Puerto Nuevo Y/Nc H K
27 Sonoran Institute N C/O-F; H L,K,E
28 TIME Y/Nc CMK H
29 AZ Trucking Association N G
30 UPRR N for RR
a Based on interviews conducted in May and June 2007
b The corridor designations are those used in Figure 3.5.
c Y/N means partial or qualified support for bypass.
Note: Interviews with State Transportation Board Members and ADOT District Engineers not included in
tabulation.
Safford and Willcox interviews were obtained later and are shown in Table 3-3.
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Table 3-2 Combined Stakeholder Responses to Potential Corridor Alternativesa
Support for Bypass: 10 Cities
5 Counties (one had weak support)
1 Pinal Partnership
Limited or No Support for Bypass: AZ Trucking Association
UPRR (for rail corridor)
TIME (wants improvements to I-10)
Nature Conservancy
Sonoran Institute
Pima County
Arizona Game and Fish Department
Puerto Nuevo
Response by Corridor
Corridorb Support Avoid
A 1 1
B 3 1
C 7 3
D 1
E 1 5
F 5
G 4
H 8 1
I 1
J 1
K 8 7
L 2 4
M 5
N 1
O 1
a Based on interviews conducted in May and June 2007
b The corridor designations are those shown in Figure 3.5.
The public comments had themes similar to the stakeholders. The public input is summarized in
Chapter 9.
The corridors were also compared to the purpose and need statement presented in Section 1.5.
The stated purpose of this study is to determine if a “New” corridor is needed as a bypass for
I-10. On this basis, it was decided that all existing highways and those that are already part of an
existing plan should be treated as part of the base or “No Build” alternative. For the purposes of
analyses, these corridors are assumed to be built to the logical maximum extent as discussed in
Section 2.3. The need for a new corridor is based upon unmet needs after these routes are built or
widened and improved.
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Based upon this determination, initial potential Corridors E, G, N, and O were eliminated from
consideration as a new corridor but are included in the No Build alternative. Corridor H is part of
the PAG planning process but is not adopted as part of the PAG Regional Transportation Plan at
the time of this writing. Corridor H received support from stakeholders and the public, could
potentially offer some relief to I-10 in Tucson, and is significantly different that all other
alternatives. Corridor H was retained for the corridor evaluation process.
Two additional corridor ideas came from the public and stakeholder meetings. Several people
suggested a direct connection between Corridor H and Corridor C west of I-10. An eastward
extension of Corridor L near Safford and then southward along US 191 was also suggested.
These two ideas appear to have merit and were included in the set of corridor alternatives to be
evaluated.
The San Pedro Valley received the most concern from the public and stakeholders. Corridors D
and K are in that valley. Based upon very preliminary evaluation and input from the public and
stakeholders, it appears that Corridor D would be more objectionable and difficult to construct
than Corridor K. As a result, Corridor K was chosen to go into corridor evaluation. The
evaluation is presented in Section 3.4 and Chapter 4 document the extent of environmental issues
and concerns in this valley. A single alternative connection concept for Corridor K to I-10 was
chosen for further evaluation in place of Corridors A, B, and J. The concept to be evaluated
further connects to I-10 near MP 336 as suggested by several people and is a relatively straight
line that would probably not encounter significant terrain issues.
In the central portion of the corridor study (Pinal County), the number of corridor alternatives
and the general locations were modified to start the corridor evaluation process. There was
strong support from the municipalities and Pinal County for one or more east-west corridors in
the Maricopa to Coolidge area to help accommodate the expected substantial urban development
and to supplement I-8 and I-10. Corridor I was eliminated from further consideration because it
does not appear to offer relief to I-10. Corridor I may be considered by Pinal County for other
purposes.
The corridors selected to be included in the more detailed evaluation are described in the next
section.
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3.2 FIRST REFINEMENT OF CORRIDOR ALTERNATIVES
Based upon the review as described in Section 3.1, several corridors were selected for refinement
and are shown in Figure 3.6. This graphic was reviewed by the TAC at the June meeting and was
subsequently shown to stakeholders during interviews conducted in July 2007. Note that some of
the corridor nomenclature was modified from that shown earlier in Figure 3.5 to fit the refined
alternatives. Refer to Figure 3.6 for reference. A brief description of the alternatives is included
below:
• Corridor C – Represents the general corridor identified in the Hassayampa Regional
Framework Study. It would connect to I-10 west of SR 85 and proceed in a general
southeasterly direction, crossing SR 85 south of I-10 traversing near the northern
boundary of the Sonoran Desert National Monument passing east-west through the City
of Maricopa planning area, cross I-8 west of I-10, proceed parallel and southwest of I-10
then curve to travel eastward, cross I-10 in the Eloy planning area and proceed eastward
to connect to either Corridor F, L, or K. A variation would be to have Corridor C connect
to Corridor H and proceed west of and then south of Tucson and rejoin I-10 in the
vicinity of SR 83.
• Corridor F – Would continue the eastward direction of Corridor C in the Maricopa/Casa
Grande area and proceed eastward through the Coolidge planning area and continue
eastward crossing the San Pedro River near Mammoth and continue south of the
Aravaipa Canyon Wilderness and north of the Coronado National Forest in the Galiuro
Mountains. The corridor alternative continues eastward near Klondike and on to near
Safford where it would turn south to join US 191 south of Safford. The eastern portion of
this corridor was suggested in a public meeting.
• Corridor L – Is a variation of Corridor F that would extend southeasterly in a pass
through the upper Aravaipa Valley and the Sulpher Springs Valley to join I-10 near
Willcox.
• Corridor G – Is also a variation of Corridor F in the Casa Grande area. It would realign
I-8 starting west of I-10 and extend I-8 east of I-10 to continue as Corridor F, L, or K.
Tohono O'odham Nation
San Carlos Apache
Indian Reservation
Tucson
Marana
Eloy
Casa Grande
Phoenix
Florence
Gila Bend Coolidge
Willcox
Benson
San Xavier
Gila River
Indian Community
Safford
Maricopa
Buckeye
C
G
L
K
H
C
Figure 3.6
Corridor Alternatives - First Refinement
Legend
II--10 Phoeniix--Tucson Bypass Sttudy
0 2.5 5 10 15 20
Miles
Scale Data Source: ALRIS 1997 - 2005, Bureau of Land Management,
ADOT ATIS 2005, ADOT HPMS 2005, USGS,
Bureau of Transportation Statistics
P:\TRANSPORTATION\ADOT_TPD\23445042_I-10_Phx_Tucson_Bypass_Study\Docs\Final Reports\Figures\Fig3.6_Refined_Corridors.pdf (ai)
C
F
G
H
K
L
Refined Corridor Segments Planned Corridors
Major Rivers
City Limits
BLM
U.S. Forest Service
National Park Service
USFWS National Wildlife Refuge
American Indian Res.
Military
State Trust
Local or State Parks
Other; Private
Disclaimer:
While every effort has been made to ensure the accuracy
of this information, the Arizona Department of Transportation
makes no warranty, expressed or implied as to its accuracy
and expressly disclaims liability for the accuracy thereof.
F
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• Corridor K – Represents what appears to be the potentially most acceptable corridor in
the San Pedro Valley. It would start at either Corridor C, G, or F and extend south-eastward
in the vicinity of Mammoth or San Manual, cross the San Pedro River and then
travel southeastward east of the river and generally parallel to the river valley and then
turn eastward at the south end of the Galiuro Mountains to connect to I-10 west of
Willcox.
• Corridor H – Represents the PAG Loop Road extended northwestward to connect to
Corridor C or directly to I-10 just north of the Pinal/Pima county boundary. It would
continue southward in the Marana planning area and the Avra Valley area, cross SR 86
and continue southward near the western boundary of the Tohono O’odham Reservation
San Xavier District. It would then turn eastward and pass through the Sahuarita planning
area and join I-10 near SR 83.
These alternative corridors provide an array of options and several combinations and
permutations to be considered and evaluated. The corridors are broad study areas and do not
represent alignments.
The study team was asked to conduct additional interviews of stakeholders during the month of
July 2007. The State Transportation Board provided a list of elected officials or agency
management level people to be interviewed. A total of 14 additional interviews were conducted
involving PAG, Pima County, Marana, Pinal County, Eloy, Maricopa, Maricopa County,
Buckeye, the Southern Arizona Leadership Council, a private consultant in Tucson, and the
Tonopah Valley. The refined set of alternatives was shown to these additional stakeholder
representatives. The results are shown in Table 3-3 and are similar to results of the interviews
conducted earlier. There is, in general, strong support for the bypass idea among the cities and
counties. Corridor H is supported by Tucson area stakeholders. Corridor G and C are supported
by central Pinal County and western Maricopa County stakeholders. There was more emphasis
from the stakeholders in this round of interviews to serving existing population centers and also
recognition that finding a path through central Pinal County will be difficult due to existing and
entitled development.
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Table 3-3 Stakeholder Responses to Refined Corridor Alternativesa
Stakeholder Support Bypass
Concept
Support Potential
Corridorsb
Avoid Potential
Corridorsb
1 PAG Y No Preference
2 Pima Countyc Y H
3 Marana Y H
4 Pinal County Y G-L; G-K, C
5 Eloy Y C
6 Maricopa Y C-K
7 Maricopa County Y H-C K, L, M
8 Buckeye Not completed
9 Tonopah Valley Y C
10 Southern Arizona Leadership Council Y H
11 Private Consultant Not Completed
12 Saffordd Y F
13 Willcoxd Y K; H L; F
a Based on interviews conducted in July 2007
b The corridors are those shown in Figure 3.6 and result from the first refinement.
c Board of Supervisors passed resolution in December 2007 opposing new corridors in Pima County for I-10 Bypass.
d Positions were confirmed with city managers in December 2007.
Two people were interviewed at PAG, Pinal County, and Maricopa County for a total of 14 interviews.
Interviews with representatives of Safford and Willcox were not completed during the first round
of meetings. The city managers were contacted in December after the public meetings. Their
responses are summarized as lines 12 and 13 in Table 3-3.
3.3 CORRIDORS FOR EVALUATION – SECOND REFINEMENT
The alternative corridors presented in Section 3.2 and shown in Figure 3.6 were further refined
based on additional data incorporated into the GIS database. The corridors were completely re-labeled
with letter and number designations to provide individual segments that can be combined
and described for the evaluation. These refined alternative corridors and the new labeling system
is shown in Figure 3.7.
The GIS database was compiled from several data sources following the input provided by
agency, jurisdiction, and other stakeholder or interested party comment. The data provided by
these parties included constraints such as National Monuments, Wilderness Areas, Local and
State Parks, entitled lands, existing land cover, and protected lands. The provided data were
normalized for projection system, data format, and assigning a common valuation field.
Table 3-4 provides a list of data categories used in the analysis modeling.
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Table 3-4 GIS Data Sources
Data Category Description of Data Stakeholder
Transportation Airports Bureau of Transportation Statistics Railroads Bureau of Transportation Statistics
Arizona Protected Lands The Nature Conservancy
ACECs, National Monuments,
Wilderness Areas
Special Bureau of Land Management
Designations or
Special Interest SRP Mitigation Properties Salt River Proje